D. J. SCOURFIELD ON EPHIPPIA OF LYNCEID ENTOMOSTRACA. 237 



Chydorus barroisi (Richard). 



The ephippial female of this species, some examples of which, 

 from Itatiba in Brazil, have been sent to me by Professor Sars, 

 differs considerably in shape from the ordinary female, for the 

 back, instead of being evenly rounded, is flattened in the anterior 

 half and distinctly angulated near the middle (Fig. 35). The 

 dorsal thickening is strong, and much longer, comparatively, than 

 in other species of the genus. The darkening of the shell, too, is 

 somewhat peculiar. It consists of large reddish-brown hexagonal 

 spots in addition to a general deepening of colour, producing a 

 very characteristic appearance. The shell sculpture, normally 

 minute hexagonal markings, is apparently modified over the 

 darkened area to agree with the much larger hexagonal arrange- 

 ment of the coloration ; and the chitin of the darkened area is 

 minutely pitted. The nature of the inner membranes could not 

 be made out, nor could a line of weakness be traced in these 

 preserved specimens. 



Chydorus eurynotus Sars. 



The ephippium of this species from Sao Paulo, kindly sent to 

 me by Professor Sars, is very similar to that of C. sjohaericus, 

 except that the ventral margins of the valves break away 

 entirely, right down to the posterior ventral angle. The line of 

 separation is marked by a row of minute, loosely connected 

 chitinous plates. The shell is not very much darkened, and the 

 dorsal thickening is not so strong as in C. sjyhaericus, although 

 somewhat longer. There are hexagonal, bufc very indefinite 

 markings over the surface, and the chitin is minutely pitted. 

 Surrounding the e^g are some very delicate inner membranes. 

 The female, after throwing off an ephippium, has the back 

 deformed in almost exactly the same way as C. s-phaericus. 



From the foregoing details regarding the ephippia of what 

 may probably be regarded as a fairly representative collection 

 of genera and species of the Lynceidae, we can now formulate 

 the general characteristics of these productions in the family with 

 some approach to certainty. The chief of these are, I think, 

 as follows. 



(1) The ephippium is, as a rule, composed of a large portion of 

 the original shell. 



JouRN. Q. M. C, Series II.— No. 50. IG 



