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



back the inner layer of the skin could be seen to be swelKng out 

 to a considerable thickness, though still quite soft and pliable. 

 The ephippium, when thrown off, was exactly similar to the 

 one figured. One fact in connection with the moulting of this 

 ephippium may be worth recording. It was attached so firmly 

 to the bottom of the glass tube in which the experiment had 

 been made, that I could not move it with a little brush, but had 

 to take a hooked needle and tear it away forcibly. The adhesion 

 of Lynceid ephippia to the sides of the vessels in which Entomo- 

 straca are kept is not at all an uncommon phenomenon, and 

 it has already been referred to, but this was the most tenacious 

 attachment that I have observed. I believe that the mass of 

 threads and cellular matter protruding from the anterior part of 

 the ephippium is the means by which the attachment takes place. 



Alona costata Sars. 

 The ephippium of this species, before the ventral portions of 

 the valves have become quite detached, is shown in Fig. 15. 

 There is very little alteration of the shell, the surface -markings 

 remaining as in the ordinary female, but there is a considerable 

 amount of darkening over the egg and in the dorsal region 

 generally. The chitin of the back is thickened as usual, and 

 is of a dark yellowish -brown colour. Surrounding the egg there 

 is a copious supply of exuviated membranes, but their arrange- 

 ment is very irregular, although they probably form a closed inner 

 case. Some of the membranous material may project beyond the 

 shell, as indicated. I have not been able to examine a living 

 ephippial female, but from the appearance of the edges of the 

 crack between the ephippium and the ventral parts of the shell, 

 there can be no doubt that a line of weakness is formed before 

 the moulting of the ephippium takes place. In the figure little 

 imperfectly connected pieces of chitin can be seen still adhering 

 to a part of one edge of the crack, showing that much the same 

 formation takes place in this species as in Camptocercus rectirostris 

 and Acroperios harpae. When the ventral portions of the valves 

 become detached they break off abruptly a little way in front of the 

 posterior ventral angle, in the position indicated by the dotted line. 



Alona rectangula Sars. 

 This is one of the smallest species of the genus, and its ephippium 

 is correspondingly minute, never much exceeding y^^ in., and being 



