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. 



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