174 Records of the Indian Museinn, |Vol. V, 



pairs of peraeopods, a considerable amount of variation is some- 

 times to be found. 



Three of the species in the collection are regarded as new, an 

 interesting variation in the petasma of G. sciitatus, Bouvier, is 

 noticed and a fresh description is given of G. carinatus, Smith, a 

 remarkable form which combines in one species the characters both 

 of Geiuiadas and of the allied genus Bcnthcsicynms. 



The number of specimens examined is unfortunatel}' small and 

 this is doubtless due to the fact that the ' Investigator ' collections 

 were made almost entireh^ by means of trawls fishing on the 

 bottom. The species of Geiuiadas, as far as is at present known, 

 are entirely pelagic in habit and their occasional appearance in 

 bottom hauls is explained by the fact that they are sometimes 

 caught while the net is being hauled to the surface. 



All the species mentioned in this paper possess podobranchs 

 on the first three pairs of peraeopods and are in consequence 

 members of the genus Gennadas, sensu stricto. 



The measurements given represent the total length, and were 

 taken from the apex of the rostrum to the tip of the telson, with 

 the animal extended as nearly as possible in a straight line. 



Gennadas alcocki, sp. nov. 

 (Plate xiii, figs. 5—8.) 



St. III. — Bay of Bengal, 12° 50' N., 90° 52' E., 1,644 fathoms. 

 One male, 36 mm. 



St. 103. — Bay of Bengal, 15° 14' N. , 81° 9' E., 1,260 fathoms. 

 One female, about 25 mm. 



St. 108.— Off C. Comorin, 7° 4' N., 76° 34' 15" E-, 1,043 fath- 

 oms. One male, 34 mm. 



St. 309. — Near the Andaman Islands, 10° 9' N., 93° 2' 15" E., 

 765 fathoms. One male, 34 mm. 



The rostrum is well elevated above the dorsal carina of the 

 carapace and bears the usual small tubercle behind the dorsal 

 tooth. The antennary and infra-antennary angles are acute and 

 the branchiostegal spine is small but evident. The cervical and 

 post-cervical grooves of the carapace are well marked; dorsally, 

 the distance between them is only about one-fifth of the distance 

 from the post-cervical groove to the hinder margin. The median 

 carina is visible throughout the length of the carapace. 



The second joint of the antennular peduncle, measured 

 dorsally, is fully two-thirds the length of the ultimate joint. The 

 antennal scale (fig. 7) is a little more than three times as long 

 as wide ; the outer margin is somewhat convex and termi- 

 nates in a spine which extends be^'ond the narrow apex of the 

 lamella. 



The ultimate joint of the mandibular palp varies in length, 

 but is, in all cases, shorter than the greatest width of the basal 

 joint. In the second maxilla the anterior lobe of the internal 



