220 D. J. SCOURFIELD ON EPHIPPIA OF LYNCEID EXTOMOSTRACA. 



and in a subsequent paper gave a detailed description of the 

 ephippium of Leydigia acanthocercoides (10). 



Having now considered the small literature connected with 

 Lynceid ephippia, attention may be turned to the more essential 

 object of this paper, which is, to describe and figure as fully as 

 possible the ephippia of numerous species, in order that some 

 idea may be obtained of their general characteristics and of the 

 range of their principal variations. I propose, therefoi-e, to 

 commence at once with the description of the ephippia, or 

 ephippial females, of those species I have actually examined, 

 taking them as far as possible in the order in which they aro 

 arranged by Lilljeborg (4). 



Eurycercus lamellatus (0. F. ]Miiller). 



The ephipi^ial female of this giant Lynceid exliibits a well- 

 defined area of a deep reddish-brown colour extending nearly 

 three-quarteis of the distance across the valves from the 

 dorsal margin. The exact shape and position of the darkened 

 area can best be understood by a reference to Fig. 1. The 

 ordinary shell markings, a very faint irregularly hexagonal 

 meshwork, seem to be increased in strength over the darkened 

 area — at least they are quite evident in the specimens of 

 ephippial females kindly sent to me by Professor Sars from 

 Finmark — whereas in our British specimens of the oidinary 

 female the hexagonal markings are rarely if ever present. 

 A considerable thickening of the substance of the shell has 

 also probably taken place, and the structure of the chitin 

 is no longer homogeneous, but contains a large number of 

 exceedingly minute pits or cavities. Along the dorsal line 

 of the shell the chitin is clearly seen to be much increased in 

 thickness. ThLs is indicated in the figure by the double line 

 along the back. 



But the most remarkable fact about the ephippium of Euryce)'cus 

 lamellatus, and one which is probably quite characteristic of 

 the genus, if not of this species, is that it is designed to contain 

 a large number of winter eggs. Schodler records from two 

 to ten, Weismann says up to eight, and I have seen as many 

 as thirteen in one of the ephiiDpial females sent by Professor 

 Sars. With one possible exception, to be referred to later 

 in connection with C amptocercus rectirostris, every other Lynceid 



