D. J. SCOURFIELD ON EPHIPPIA OF LYNCEID ENTOMOSTRACA. 231 



the actual ephippium is smaller, comparatively, than in the case of 

 any other Lynceid, and it is approximately semicircular in 

 outline. The dorsal margin is strongly chitinised, and the whole 

 ephippium is much darkened, and probably also thickened. 

 The shell markings, consisting of parallel longitudinal stripes with 

 extremely fine striae between them, are not obliterated, but are 

 somewhat altered, as if by irregular deposits of chitin. 



The ephippium and its hooked processes become detached from 

 the rest of the valves by the falling away of a special line of 

 loosely connected pieces of chitin developed, before moulting takes 

 place, along the ventral margin of the ephippium and completely 

 round the free margins of the shell (Fig. 20). Within the outer 

 case, and completely surrounding the egg, there is an abundant 

 development of cellular tissue, forming a kind of " packing," 

 similar, in some respects, to what occurs in Alonopsis amhigua 

 and Alona tenuicaudis. Some of this may project from between 

 the ventral edges of the ephippium, as shown in the figure. 

 Altogether this ephippium is one of the most peculiar, and 

 possibly also the most highly evolved, of all the Lynceid ephippia. 



Dr. Yosseler has given a figure of the ephippium of this, or an 

 allied species, in Lamport's " Das Leben der Binnengewasser," 

 1899, p. 257, but without a detailed description. 



Grwptoleberis testudinaria (Fischer). 



My drawing of the ephippium of this species, Fig. 21, was 

 made in 1892, before I had given any special attention to this 

 subject. It shows, however, that, while there is no evident 

 alteration of the sheU sculpture, the chitin is thickened at the 

 back; that a rather small part of the ventral margin of the 

 shell becomes detached, and that there are probably some inner 

 membranes surrounding the e^g. The ephippium was a little 

 darkened, as is commonly the case ; and I noted that the keel 

 of the shell did not seem so evident as usual in this species, 

 indicating, perhaps, that there may be^ some modification in this 

 respect. 



AloneMa rostrata (Koch). 



Figure 22 represents the ephippium of this species. It is very 

 much darkened, especially towards the back, but the surface shell 

 sculpture is not appreciably modified, and the dorsal margin is 

 but very little thickened — at least, it does not show such a clear 



