316 "ENDEAVOUR" SCIENTIFIC RESULTS. 



Morocco, 500-1,300 meters (Bouvier) : and West 

 Atlantic. Gulf of Darien, 155 fathoms; "Albatross" Stn. 

 2143 (Smith). 



Remarks. The finer points of distinction elaborated 

 by Kemp and Sewell, and upon which this, species is 

 separated from A. rostridentata hold good for the 

 "Endeavour" specimens and distinguish them from that 

 species. The latter, however, seems to be hardly more 

 than a variety of the former, especially in view of any 

 lack of differentiation in either petasma, thelycum, or 

 oral appendages (vide Kemp and Sewell). 



Smith's Aristeus f foliaceus, a form somewhat inter- 

 mediate between the two, is most like, and no doubt is a 

 true A. folia cea- (see lateral view photograph of Smith's 

 specimen, a small male, on Plate Mi.). Its ptery 

 gostomiau region is but 3-33 times as long as its greatest 

 width, as compared with a length not exceeding 2-5 times 

 for A. rostridentata, and more than 3-5 times in 

 A. foliacea (vide Kemp and Sewell the length of the 

 pterygostomian region is "measured from the antero- 

 lateral margin of the carapace to the postero-dorsal end 

 of the hepatic groove"). In the "Endeavour" specimens, 

 the length of the pterygostomian region is from 3-5 to 

 about 4 times its greatest width. The telson, like that 

 of A. foliacea, falls about one-fifth of its length short 

 of the tip of the inner uropod. The relation of the length 

 of the dactyls of the last two pairs of legs to the length 

 of the propodi, approaches that of A. foliacea, being less 

 than one-half their length. The dactyls of these legs in 

 Smith's specimen are now wanting, but fortunately his 

 very complete measurements included their various 

 lengths. In A. rostridentata they appear to measure 

 more than half the length of their respective 

 propodites. Unlike either of these species, Smith's 

 specimen has a more slender sixth abdominal somite, 

 which is a little more than 1-75 times as long as its 

 greater depth. In both A. roxtridcntata and A. foliacra 

 the length of the sixth abdominal somite varies from 1-5 

 to 1-66 times its greatest depth. 



Measurements. Of six of the "Endeavour" speci- 

 mens enumerated above, and the one (Cat. No. 7264, 

 U.S.N.M. ) upon which Smith's description of Aristeus f 

 foliaceus was based; the measurements are in millimetres. 



