166 BRITISH ENTOMOSTRACA. 



consist of exactly the same organs as in the animals of that 

 genus, though, from their extreme minuteness and want 

 of lengthened opportunities for examination, I have not 

 been able to make out all the parts. The palpiferous 

 mandibles, and the first pair of jaws with their branchial 

 plates, are the only parts I have clearly distinguished, 

 and they resemble in almost every respect the correspond- 

 ing organs of the Cyprides. 



The mandible (t. XX, f. 5<?) is formed of two pieces : the 

 larger of the two, or proper mandible, as in the Cypris, 

 being terminated at the superior extremity by a sharp 

 point, and at the lower or incisive extremity by about six 

 or eight pretty strong teeth ; while the other part, the 

 palpus, consists of three or four joints, plentifully supplied 

 at the extremities of the articulations with numerous setae, 

 and a small branchial plate of one joint attached to the 

 first articulation. The first pair of jaws (t. XX, f. 5 d), as 

 in tlie Cypris, consists also of two parts, the square plate, 

 with the four fingers, the superior of which has two joints, 

 while the others have ouly one, and are all terminated by 

 a tuft of seta3 ; and the branchial plate attached, of an 

 elongated oval form, furnished with fourteen long setae, 

 which are given off from both sides. As these organs are 

 so very similar to the corresponding organs in the Cypris, 

 I have no doubt that the other parts (the lips and second 

 pair of jaws) are also alike, and therefore that the suppo- 

 sition of Desmarest, with respect to some of the inter- 

 mediate feet being peculiar organs, is incorrect, and that 

 as their use and situation indicate, they are all true feet, 

 and used solely for locomotion, the posterior pair perhaps 

 serving, in addition, one of the uses of the tail of the 

 Cypris, that of cleaning the inside of the shell, for which 

 they are well adapted, from theu' length and the great 

 degree of mobility they possess. 



The appendix, or short tail, is of such an irregular 

 figure, that until better opportunities occur for examina- 

 tion, I shall not attempt a minute description. The in- 

 ternal anatomy I have not succeeded in making out at all, 



