598 THE VOYAGE OF H.M.S. CHALLENGER. 



The second pair of gnathopoda has the terminal joint about three times the length of 

 the penultimate, it is spatulifonu and has the distal margin fringed with small spines. 



The first pair of pereiopoda is short, robust and chelate ; the carpos being as long as 

 the palm of the propodos and subequal with the meros. The second pair is long and 

 slender, minutely chelate, and has a carpos that is half as long again as the meros, and is 

 divided into seven unecpial articuli. The posterior three pairs of pereiopoda are 

 short and robust, and have the propodal extremity of the carpos projecting over the 

 articulation ; the propodos is fringed with spines on the flexor margin, and the dactylos 

 serrate and biunguiculate. 



The rhipidura has the outer plates bisected by a diaeresis, and the external margin 

 armed with a minute spine. The telson is longer than the lateral plates, and is furnished 

 with four dorso-lateral spinules, and terminally with two spines and a few hairs. 



Bell's description and figure were evidently taken from the animal which is pre- 

 served in the collection of the British Museum. 



Milne-Edwards' description was probably drawn from an Arctic specimen. It differs 

 from the figure given by Leach in certain minute details ; for instance, he says that the 

 extremity of the rostrum is truncated ("tronque au bout"), armed on the upper surface 

 with four or five teeth on the carapace and seven or eight very small teeth on the rostrum, 

 and on the lower with two teeth, the anterior of which is separated from the apex by 

 some little teeth. 



The third somite of the pleon posteriorly projects as a great hooked tooth, and the 

 telson is furnished with four pairs of little spines. 



Milne-Edwards' specimens are recorded from Greenland and Iceland. Sowerby 

 obtained his from Scotland, Leach's came from the Firth of Forth, and Bell received two 

 that were dredged by Mr. MacAndrew off the coast of Shetland. 



Professor Owen figures and describes x this species as having the carapace armed with 

 teeth from the posterior margin to the apex of the rostrum (PI. C VI. fig. 2), they decrease 

 gradually in importance anteriorly, and on the under margin there are two teeth with- 

 out the small series shown in Leach's figure, and he remarks that the general form of 

 the rostrum agrees with that figured by Leach, but that many have it simply emarginate 

 at the apex and not serrulate. The third somite of the pleon in Professor Owen's figure 

 has the dorsal surface projecting posteriorly in the median line as a strong and elevated 

 tooth. This peculiar feature is made a specific character in the description of this species 

 under the name of Hiyypolyte sowerbyi by Milne-Edwards, 2 and also in the description 

 and figure of Hippolyte spi7ins by Bell, 3 who states that it is carinated, while Owen 

 figures it as an elevated and prominent tooth, and Milne-Edwards says that it is 

 prolonged in the form of a great hooked tooth which resembles " un bee de seiche " 

 advancing above the following somite. 



1 Loc. cit. a Loc. cit. 3 Loc. cit. 



