424 



ATHEKINIDyE. 



Atherina liyalosoma (Cocco), Facciola, Nat. Sicil. iv. 1885, p. 239. 



Atherina riqueti, Roule, Zool. Anz. 1902, p. 262, fig., and C. R. Ac. Sci. cxxxvi. 1903, p. 824, and 



cxxxvii. 1903, p. 1276. 

 Atherina sardinella, H. W. Fowler, t. c. p. 729, pi. xli. 



This widely distributed Mediterranean species is introduced here among the fresh- 

 water fishes because it has been found in fresh waters, even in lakes cut off from access 

 to the sea, in the south of France, in Spain, in Italy, and in Algeria. In Egypt it has 

 only been found hitherto in salt water, but so far inland as Lake Temsah, where it 

 occurs in the company of Cyprinodon fasciatus and Mugil capito. Its exclusion from 

 this work would therefore hardly be justified. 



I have taken the species A. mochon in a very broad sense. The distinction of the 

 forms named A. rissoi, A. lacustris, A. riqiieti, A. sardinella, &c. does not seem to me 

 to rest on characters of sufficient importance to justify specific rank, and I should 

 prefer to look upon them as races. From this point of view the Egyptian form 

 deserves a name, which I propose to be var. c&gyptia, the chief distinctive characters 

 being the small size, comparable to that of the var. riqueti, and the small number of 

 scales (20 to 24) round the body in front of the ventral fins. The following definition 

 is taken exclusively from Egyptian specimens, but measurements and numbers of scales 

 and fin-rays of examples from other points of the habitat of the species are given for 

 the purpose of comparison. 



Tie. 31. 



Atherina mochon, var. cegyptia. Natural size. 



Depth of body four and two- thirds to six times in the total length, length of head 

 four to four and a half times. Snout rounded, shorter than the eye, which equals the 

 length of the postorbital part of the head and the width of the interorbital region, 

 which is flat, with a low median keel ; lower jaw slightly projecting ; mouth extending 

 to below the anterior fourth of the eye ; teeth small, conical, forming a narrow band. 

 Gill-rakers nearly as long as the gill-fringes, 16 to 20 on the lower part of the anterior 

 arch. First dorsal fin with 6 or 7 rays, originating nearer the end of the snout than 

 the root of the caudal fin ; second dorsal fin with a feeble spine and 11 or 12 articulated 

 rays, originating a little further back than the anal, which has a feeble spine and 12 or 

 13 articulated rays. Pectoral fin shorter than the head, extending to above the root of 

 the ventral, which is a little in advance of the dorsal. Caudal fin deeply forked. 



