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A HISTORY OF LEICESTERSHIRE earlier described by de Geer as bispinosa^ is now admitted to be only a variety of M tiller's mucronata. The typical form, Lilljeborg says, is in profile so peculiar that it can at once be distinguished from all others; the body is short, almost oval, in front obtusely pointed, with almost straight lower margin behind the head ; above, behind the head, there is a deep con- striction ; the lower hinder corners of the shell are each provided with a more or less long pointed process, the lower front corners having a more or less angular prominence. The variety sometimes has the hinder processes much elongated, and the frontal angle produced into a long, straight, acuminate horn, making the general appearance very different from the normal, with which it is neverthe- less connected by many intermediate gradations in different individuals. 17 Simosa vetula (O. F. M.) is recorded by Mr. Scourfield under the name Simocepbalus vetu/us, which it long enjoyed, until Dr. Norman recently pointed out that the generic part of the title was preoccupied. Flat-head, or snub- nose, the meaning of the name, may allude either to the non-carinate character of the head or to the bluntness of the rostrum. In this genus and the next the ephippium, as the case for the winter eggs is called, contains only one egg, whereas that of Daphnia has two. In Ceriodaphnia Mr. Garnar records C. quadrangula (O. F. M.), for which Mr. Scourfield substitutes C. pulchella, Sars, with the explanation that Mr. Garnar had relied on one of Mr. Scourfield's own papers, in which the two titles were transposed. Mr. Scourfield himself records C. mega/ops, Sars, and C. affinls^ Lilljeborg. These four species are distinguished by the last-named author as follows : C. mega/ops [of which the original and therefore correct name is C. megops has the hinder or upper margin of the tail near the apex abruptly notched or angled, the other three species having no such abrupt notching. But in C. quadrangula the margin in question within the spines is sinuate, while in C. pulchella and C. affinis it is not sinuate. Lastly, the head in C. pulchella is notably inflated, and sometimes angled, but it is not inflated in C. affinis. This species Mr. Scourfield considers the best acquisition in his list ' from a collector's point of view. 19 In the family Bosminidae both our authorities record Bosmina /ongirostris, Mr. Scourfield adding that B. cornuta is included. Several varieties of the species have been named. Between the two with which we are here con- cerned the distinction is given that B. longirostris (O. F. M.) in the restricted sense has the first antennae of the female little curved, and not hook-shaped, but B. cornuta (Jurine) has them very much curved and more or less hook- shaped, and after all there are intermediate forms connecting the two. As this little species with rounded profile seldom exceeds and does not always attain the length of -5 mm. that is, the fiftieth of an inch it will be under- stood that the marks of variation are tolerably microscopic. It is gregarious and widely distributed, being known not only from most parts of Europe, but also from Siberia, Central Asia, and the United States of America. 20 The family Macrotrichidae is represented here by the three species which Mr. Garnar obtained from Seddington Reservoir. The three genera to which these species belong agree in having an unlooped intestine, which is also without coecal appendages in front. They are distinguished one from another by the circumstance that the outer branch of the second antennae has "CfatoctraSueciaf,i$i,i5s. "Ibid. 185. "Inlitt. 22 July, 1906. lo ClaJoceraSueciae, 226, 235. IO2