274? Notes on Hzppdlyte rubra. 



two), agreeing with Mr. Hailstone's description above (p. 271.)» 

 Is it in an adult state ? the length being very short for one of 

 the PalaemonzW^. It is to be borne in mind that the above 

 figure is taken from a mutilated individual, in which the two 

 anterior pairs of legs are broken off: these are represented as 

 detached. Mr. Hailstone having omitted to complete his 

 account by prefixing a name to the description, I have sup- 

 plied the want by employing that given above, suggested by 

 the two spines on the shell. 



[Notes upon Hippolyte ? rubra, by Mr. Westwood.~\ — This 

 animal differs so completely from Hippolyte, not only in the 

 characters mentioned by Mr. Hailstone, but also in the 

 general slender form of the body, the abdomen not being 

 gibbose in the middle, and in the length of the superior 

 antennae, that I should not hesitate to form it into a separate 

 genus; that is, on the supposition that the latter organs are 

 correctly described as only furnished with two filaments. 

 This is, indeed, an important character ; as the distribution of 

 the genera of this family adopted by the best crustaceologists 

 depends on the presence of two or three filaments. If the 

 description be correct, this new genus must be arranged in a 

 small group of genera consisting of Pelias, Pontonia, Hip- 

 polyte, Alpheus, and Gnathophyllum, all of which have the 

 two anterior pairs of legs didactyle. In Pelias, however, 

 these legs are nearly of equal size ; the second pair being the 

 thickest, with the wrists not annulose. In Pontonia, also, 

 the wrists are similarly formed ; but the second pair of legs 

 is excessively large. Alph^us * comes nearest to this new 

 genus; but its types are large Indian species having the first 

 pair of legs large, but very unequal in size, and much longer 

 than the second pair. In Gnathophyllum the wrists are not 

 annulose, and the external foot-jaws are dilated. 



If, on the other hand, the superior antennae have three 

 filaments, the genus comes very close to A'thanas, in which, 

 however, the eyes are exposed, the fore legs not so large, and 

 the rostrum long; but there is a genus, omitted by Latreille, 

 which appears to agree in every respect with that under con- 

 sideration : it is the Cryptopthalmus of Rafinesque [Precis de 

 Decouvertes, 1814), which has, as the name implies, the eyes 

 concealed by the fore part of the shell. The specific name, 

 C. ruber, also points out the apparent identity ; but the 

 upper antennae are stated to have three filaments. Conceiving 

 it not improbable that these descriptions may relate to the 

 same animal, I have employed the same specific name for the 



* The Alpheu-s aculeatus O. Fabr., and A. polaris, both figured by 

 Sabine in the Voyage to the North Pole, belong to the genus Hippolyte. 



