12 6 Mej?ioir Sears Foundation fo?' Marine Research 



measured from posterior end of slit-like vent to caudal notch, 1.3 in length of disc. 

 Caudal fin broad, almost as deep as long. The dorsal and ventral edges nearly straight, 

 posterior margin rounded. Upper lobe a little longer and more acute than lower. Skin 

 smooth. Pelvic fins separate one from the other and free from the tail at their extreme 

 tips. Their outer anterior margins not concealed by posterior end of pectorals. 



Colour in Spirits. Dorsal surface light brown, overlaid with a series of darker 

 brown blotches and white and brown spots. There is a series of irregularly rounded 

 dark brown blotches arranged symmetrically along the outer margins of the pectorals 

 and pelvics, with another pair immediately in front of the eyes. Behind the spiracles 

 and covering the centre of the disc and anterior part of the tail is a series of scattered 

 dark brown spots, interspersed with some white spots and larger dark brown blotches. 

 Dorsals and caudal light brown. At the base of both dorsal fins is a dark brown blotch 

 which extends a short way on to the fins. Near the tip of each dorsal is a dark brown 

 band. The caudal fin is crossed by two brown bands, one near the base, the other near 

 the tip. A narrow band of white along the tree margins of pectorals and pelvics. Ventral 

 surface white."'®* 



Si%e. The single specimen known was 137 mm in total length and it is probable 

 that the species does not reach a large size. 



Developmental Stages. Nothing is known. The one specimen described was a 

 female, probably immature. 



Habits. There is no information as to the breeding habits or the diet of this species. 



Range. Known only from off Georgetown, British Guiana. 



Reference : 



Diplobatis pictus Palmer, Ann. Mag. nat. Hist., (12) J, 1950: 480 (descr. holotype). 



Genus Benthobatis Alcock 1898 



Benthobatis Alcock, Ann. Mag. nat. Hist., (7) 2, 1898: 144; type species, B. moresbyi Alcock. India, ofF Tra- 

 vancore Coast, 430 fathoms. 



Generic Characters. Benthobatis agrees with Narcine in its relative length of tail, 

 shapes of fins, wholly naked skin, proportions of anterior nasal flap, protractile mouth 

 with labial cartilages, and single cusp on teeth. But it diflfers from Narcine in that the 

 eyes are either entirely rudimentary or at least minute and seemingly blind, the cutaneous 

 folds along the tail are absent or replaced at most by a low fleshy ridge, and the spir- 

 acles are relatively smaller. In known species the caudal is oval, its lower posterior 

 contour continuously rounded. Pelvics attached to sides of tail to their tips in some 

 species, perhaps in alL^"' Skin in fresh specimens soft and loose, the body limp and 

 flaccid."" The rostral cartilage is like that in Narcine, but with its lateral ridges softer 



168. From Palmer, Ann. Mag. nat. Hist., (12) j, 1950: 480. 



169. This is the case in Benthobatis marcida (p. 131, Fig. 26). But the account and illustration of 5. moresbyi {AXcoA, 

 Ann. Mag. nat. Hist., [7] z, 1898: 145; 111. Zool. 'Investigator', 4, 1899, pi. 26, fig. i) fail to cover this point. 



170. This was the case in the considerable series of specimens from Cuban waters listed on p. 12S, and the skin was so 



