ORCHKSTID^. 9 



ferred upon them the popular name of Sea- ileus {Puces iU mer). 

 The origin of the generic name Talitrus signifies a '' fillip." 



2. Talitrus brevicornis. (Plate I. a, fig. 6.) 



Talitrus brcviconie, J^dtciirds, Hid. (Its Cni.sf. t. iii. p. 15. 

 Talitniti brcWcoriiis, Dti/ni, U.6'. Explor. Exptd. pi. 5G. f. 6. 



Of this species I have seen no specimen. The figure of the parta 

 which is given is taken from Dana's ' Exploring Ex2)edition of the 

 United States.' 



Edwards says that it is very like 'Talitrus Locusta, but that the 

 antennae are shorter, so much so that they barely extend to the 

 third segment of the pereion. The upper antenna in Dana's figure 

 reaches beyond the extremity of the penultimate articulation of the 

 peduncle of the lower. The female only of this species is known. 



Dana likewise considers it a true Talitrus, imless it should be tho 

 female of TaJorchestia Quoyana. 



It is taken on the coasts of the Bay of Islands, Xew Zealand 

 {Edwards; Dana). 



3. Talitrus platycheles. (Plate I. «. fig. I.) 



Talitru.s platycheles, Gueriu, Exped. Scieut. de Moree, t. iii. pt. 1, 

 sect. 2. p. 44, pi. 27. tig. 4. 



Edwards, Hist, des Crust, t. iii. p. 15. 



Of this species I have likeAvise not seen any specimen ; but, by the 

 kindness of M. Guerin, I have seen his original di-awing, and com- 

 pared it with the figure in his work, from wliich the one in our 

 plate is taken. 



The great difference, according to the author, between this species 

 and the type of the genus, exists in the somewhat larger proportion 

 of the second gnathopod in relation to the fii-st. 



M. (juerin con.sidered this so important a feature that he foiined 

 a division in the genus Talitrus to receive the new species, and 

 doubted whether he was justified in not making a genus for its recep- 

 tion. He placed the Talitri that had the fii-st gnathopod larger than 

 the second in Di\'ision A, of which the Talitrus Locusta formed 

 the type ; those that had the gnathopoda equal, he placed in Divi- 

 sion B, of which T. platycheles formed the type ; and la.stly, those that 

 had the second gnathopod larger than the tir.st, he placed in Division 

 C, of which he made Talitrus Cloquetii the type ; but this last is 

 a tiTiC Orchcslia. 



The relative proportion of the second pair of gnathopoda to the first 

 is in itself scarcely enough to warrant its being more than a variety, 

 particularly as, according to M. P^dwards's descriptioTi, the limb bears 

 the impoverished character a.s in Lociuila, being "fiat, of a membra- 

 nous consistence, and without spines." 



But a more important distinction exists in the absence of the dac- 

 tylos of the second pair of gnathopoda. 



