MUSTELUS MEGALOPTERUS. 







5 







3 







3 



6 



1 







DIMENSIONS. 



Feet. Inches. Lines. 

 Length from nose to apex of caudal 



fin 4> 



Circumference immediately before 



first dorsal fin 1 



Distance between nose and eye ... 

 Distance between nose and angle of 



mouth 



Distance between nose and nostrils 

 Distance between nose and middle 



of upper jaw 



Breadth between the angles of the 



mouth 



Distance between eye and post 



ocular spiracle 



Distance between eye and first 



branchial opening 



Distance between nose and anterior 



edge of first dorsal fin 







17 



9 











6 



Fuet. Inches. 



Distance between hinder-edge of 

 first dorsal and anterior edge 

 of second dorsal 



Distance between base of second 

 dorsal behind, and base of 

 caudal fin 



Distance between nose and an- 

 terior edge of pectoral fins 



Distance between base of pectoral 

 fin behind, and anterior edge 

 ofventrals 



Distance between base of ventrals 

 behind, and anterior edge of 

 anal fin 



Distance between posterior edge 

 of anal behind, and base of 

 caudal fin 



Length of anal appendages 



Lines 



12 9 



10 



13 9 



The chief external differences between the male and female consist in the 

 latter wanting the anal appendages, and having the fins, particularly the 

 pectoral ones, proportionably smaller. 



In the course of several years during which the fishermen of Cape Town were engaged by 

 me in collecting cartilaginous fishes, only a very few specimens of this species were obtained. 

 Their want of success, however, probably arose more from the species resorting to situations 

 little visited by fishermen during their ordinary avocations, than from the scarcity of specimens. 

 It feeds upon mollusca, Crustacea, Sfc, and in quest of these it haunts principally the rocky, or 

 broken parts of the coast. 



Specimens of this species are occasionally procured, in which the ground colour, similar to 

 that described, is freely spotted with dusky black blotches, very various as to size. 



As I have not had an opportunity of ascertaining whether the males of the species of this 

 genius are provided with sacs, similar to those which occur in several of the other genera of the 

 Squalidce, and which sacs appear to be connected with the anal appendages, I would suggest 

 the inquiry, as deserving the attention of those naturalists who have an opportunity of ex- 

 amining specimens of the European species. The sacs to which I allude, two in number, lie 

 under the skin of the abdomen, immediately in front of the anus, are of a pyriform shape, and 

 each, by means of a narrow duct, opens into the longitudinal groove, which exists on the inner 

 side of each anal appendage. In none of the sacs which I examined was I able to detect 

 any fluid beyond what was barely sufficient to lubricate their inner surfaces, and from whence it 

 proceeded I could not discover; no glandular structure was noticed. Farther enquiries, I have 

 no doubt, will shew them to be essential to the proper performance of the functions belonging 

 to the appendages; and as tending to give probability to that supposition, I may merely 

 observe that by injecting water into one of these sacs, the corresponding appendage was dis- 

 tended to a great size, and its apex expanded, flattened, and rendered well adapted for fixing 

 upon, or seizing extraneous bodies. 



