51 



themselves, is much stouter, and ends in a group of long, sharp 

 teeth. 



The following pairs of pleopods are long and slender and bear 

 fringes of long pinnate setae. A small and feeble appendix 

 interna is present on the second to fifth segments, in the female, 

 and third to fifth in the male. In the latter it is wanting on the 

 second segment. It is never more than about half the length 

 of the endopodite, and becomes smaller on the posterior seg- 

 ments. 



The exopodites of the uropods have a transverse suture. Both 

 exopodite and endopodite are strengthened by two ridges, one 

 median and the other along the outer border. The latter ends 

 in a sharp tooth. The base of the uropods also bears a spine 

 pointing backwards. The hind margins of the uropods are fringed 

 with long setae. 



The branchial formula is as follows : — 



— VII. iVIII. IX. X. XI. XII. XIII. XIV. 



Podobranchs. ep. ep. l+ep.l+ep.l+ep.l-f-ep.l-j-ep. — 



Arthrobranchs. — — 22222 — 



Pleurobranchs. — — — — 1 1 1 1 



In the females there is situated between the bases of the 

 fourth pair of thoracic legs a structure corresponding to the 

 thelycum of the Peneidae. So far as I know such an organ has 

 not hitherto been described in this species.* It consists of two 

 plates lying in contact on the sternal surface between the coxae 

 of the last two pairs of legs. At the anterior end they coalesce 

 and are rounded ; at the posterior end, on the other hand, they 

 diverge and end in narrow points beside the filth coxae. The 

 two plates are arched and rise steeply from the sternum on either 

 side. Between them there is a deep groove which is widest 

 posteriorly and gradually narrows towards the front. It leads to 

 the minute opening into the interior of the spermatheca. 



If one of the plates is removed it is found that the interior 

 is filled with a whitish friable substance, in which I have suc- 

 ceeded in finding speimatozoa. The interior of the one plate 

 is in communication with that of the other by the anterior 

 portion where they are united. 



There seems to be no doubt that the structure is a genuine 

 spermatheca. It is not merely a body produced by the close 

 adherence of two spermatophores, such >as has been erroneously 

 described as a spermatheca in some of the Eryonidae (Andrews, 

 1911), for in this case it is invariably present in females, and 

 possesses perfect bilateral symmetry, two features which are 

 wanting, for instance, in Polycheles sculptus, in which species 

 spermatophores found adhering to females have been taken 

 for a spermatheca. 



* Since writing the above I have found this structure mentioned by Gaullery 

 (l&96j. 



