200 STALK-EYED CRUSTACEA 



HEMIPENEUS Bate. 

 Ann. Mng. Nat. Hist., otli Ser., VIII. 1S6, ISSl ; Rep. ChaUenger Macrura, p. 299, 1888 [Hemipenttus]. 



Hemipeneus spinidorsalis Bate. 

 Plate L., Fig. 2. 



Ann Mag. Nat, Hist., 5th Ser., VIII. 186, 1881 ; Rep. Challenger Macrura, p. 301, Plate XLIV. 



Fig. 1, 18S8. 



3 male,?, 1 fern. 



1 fern. 



2 males. 

 1 male, 2 fern. 

 1 male, 1 fem. 

 1 male. 



Tliis species, the type of the genus Hemipeneus, was discovered by the 

 naturalists of the " Challenger " Expedition near Tristan d'Acunha in the 

 South Atlantic, and near the Philippine Islands. Three specimens were 

 captured, all at great depths (1,900 and 2,050 fathoms). Bate's figure was 

 drawn from a small specimen, 57 mm. in length. The differences apparent 

 when one compares this figure with the much larger " Albatross " specimens 

 may be plausibly attributed to the disparity of age and to errors of the 

 draughtsman. The great length of the ischium joint of the chelipeds, a 

 feature not mentioned in Bate's description, nor seen in any other species of 

 the genus, is doubtless due to an error in the drawing. In the " Albatross " 

 examples the median dorsal line of the carapace is distinctly convex and 

 rises into a low car'na which is continuous from the base of the rostrum to 

 the posterior border of the carapace. The dorsal carina is apparent also on 

 the posterior half of the third, fourth, and fifth abdominal segments, and, to 

 a greater degree, through the whole length of the sixth abdominal segment. 

 The eye-stalks are flattened horizontally, and furnished with a small tubercle 

 on the middle of the internal margin. The flagellum of the second antenna 

 is enormously long, much more than twice the lengtli of the body. The meri 

 of the chelipeds are compressed. 



The rostrum of the adult male varies in length from one third to nearly 

 one half the length of the remaining portion of the carapace. It is always 

 much shorter than the antennular peduncle. In the adult female, on the 

 contrary, the rostrum is much longer than the antennular peduncle, varying 



