animals from which it could not possibly receive any harm, and is hardly limited to any season of the year.
King-Bird.
In several respects both of these birds, with several of their allies, resemble some of the shrikes; but it must be clearly understood that the likeness is but of analogy, and that there is no near affinity between the two families Laniidae and Tyrannidae, which belong to wholly distinct sections of the great Passerine order; and, while the former is a comparatively homogeneous group, much diversity of form and habits is found among the latter. Similarly many of the smaller Tyrannidae bear some analogy to certain Muscicapidae, with which they were at one time confounded (see Flycatcher), but the difference between them is deep seated.[1] Nor is this all, for out of the seventy genera, or thereabouts, into which the Tyrannidae have been divided, comprehending perhaps three hundred and fifty species, all of which are peculiar to the New World, a series of forms can be selected which find a kind of parallel to a series of forms to be found in the other group of Passeres; and the genus Tyrannus, though that from which the family is named, is by no means a fair representative of it; but it would be hard to say which genus should be so accounted. The birds of the genus Muscisaxicola have the habits and almost the appearance of wheat-ears; the genus Alectorurus calls to mind a water-wagtail; Euscarthmus may suggest a titmouse, Elainea perhaps a willow-wren; but the greatest number of forms have no analogous bird of the Old World with which they can be compared; and, while the combination of delicate beauty and peculiar external form possibly attains its utmost in the long-tailed Milvulus, the glory of the family may be said to culminate in the king of king-birds, Muscivora regia. (A. N.)
KING-CRAB, the name given to an Arachnid, belonging to
the order Xiphosurae, of the grade Delobranchia or Hydropneustea.
King-crabs, of which four, possibly five, existing species
are known, were formerly referred to the genus Limulus, a name
still applied to them in all zoological textbooks. It has recently
been shown, however, that the structural differences between
some of the species are sufficiently numerous and important to
warrant the recognition of three genera—Xiphosura, of which
Limulus is a synonym, Tachypleus and Carcinoscorpius. In
Xiphosura the genital operculum structurally resembles the
gill-bearing appendages in that the inner branches consist of
three distinct segments, the distal of which is lobate and projects
freely beyond the margin of the adjacent distal segment of the
outer branch; the entosternite (see Arachnida) has two pairs
of antero-lateral processes, and in the male only the ambulatory
appendages of the second pair are modified as claspers. In
Tachypleus and Carcinoscorpius, on the other hand, the genital
operculum differs from the gill-bearing appendages in that the
inner branches consist of two segments, the distal of which
are apically pointed, partially or completely fused in the
middle line, and do not project beyond the distal segments
of the outer branches; the entosternite has only one pair of
antero-lateral processes, and in the male the second and third
pairs of ambulatory limbs are modified as claspers. Tachypleus
differs from Carcinoscorpius in possessing a long movable spur
upon the fourth segment of the sixth ambulatory limb, in having
the postanal spine triangular in section instead of round, and the
claspers in the male hemichelate, owing to the suppression of the
immovable finger, which is well developed in Carcinoscorpius.
At the present time king-crabs have a wide but discontinuous
distribution. Xiphosura, of which there is but one species,
X. polyphemus, ranges along the eastern side of North America
from the coast of Maine to Yucatan. Carcinoscorpius, which is
also represented by a single species, C. rotundicauda, extends
from the Bay of Bengal to the coast of the Moluccas and the
Philippines, while of the two better-known species of Tachypleus,
T. gigas (= moluccanus) ranges from Singapore to Torres Straits,
and T. tridentatus from Borneo to southern Japan. A third
species, T. hoeveni, has been recorded from the Moluccas. But
although Xiphosura is now so widely sundered geographically
from Tachypleus and Carcinoscorpius, the occurrence of the
remains of extinct species of king-crabs in Europe, both in
Tertiary deposits and in Triassic, Jurassic and Cretaceous strata,
suggests that there was formerly a continuous coast-line, with
tropical or temperate conditions, extending from Europe westward
to America, and eastward to southern Asia. There are,
however, no grounds for the assumption that the supposed
coast-line between America and Europe synchronized with
that between Europe and south Asia. King-crabs do not appear
to differ from each other in habits. Except in the breeding
season they live in water ranging in depth from about two to six
fathoms, and creep about the bottom or bury themselves in the
sand. Their food consists for the most part of soft marine
worms, which are picked up in the nippers, thrust into the
mouth, and masticated by the basal segments of the appendages
between which the mouth lies. At the approach of the breeding
season, which in the case of Xiphosura polyphemus is in May, June
and July, king-crabs advance in pairs into very shallow water
at the time of the high tides, the male holding securely to the
back of the female by means of his clasping nippers. No actual
union between the sexes takes place, the spawn of the female
being fertilized by the male at the time of being laid in the sand
or soon afterwards. This act accomplished, the two retreat
again into deeper water. Deposited in the mud or sand near
high-water mark, the eggs are eventually hatched by the heat of
the sun, to which they are exposed every day for a considerable
time. The newly hatched young is minute and subcircular in
shape, but bears a close resemblance to its parents except in the
absence of the caudal spine and in the presence of a fringe of
stiff bristles round the margin of the body. During growth it
undergoes a succession of moults, making its exit from the old
integument through a wide split running round the edge of the
carapace. Moulting is effected in exactly the same way in
scorpions, Pedipalpi, and normally in spiders. The caudal spine
appears at the second moult and gradually increases in length
with successive changes of the skin. This organ is of considerable
importance, since it enables the king-crab to right itself when
overturned by rough water or other causes. Without it the
- ↑ Two easy modes of discriminating them externally may be mentioned. All the Laniidae and Muscicapidae have but nine primary quills in their wings, and their tarsi are covered with scales in front only; while in the Tyrannidae there are ten primaries, and the tarsal scales extend the whole way round. The more recondite distinction in the structure of the trachea seems to have been first detected by Macgillivray, who wrote the anatomical descriptions published in 1839 by Audubon (Orn. Biography, v. 421, 422); but its value was not appreciated till the publication of Johannes Müller’s classical treatise on the vocal organs of Passerine birds (Abhandl. k. Akad. Wissensch. Berlin, 1845, pp. 321, 405).
