471 



symphysis and the vent is covered by rhombic scales, the medial 

 series of which contains the largest, the posterior being as large as 

 one of the ventral shields. The series of femoral pores meet at a 

 right angle. 



The fore-leg reaches to the extremity of the snout, if laid forwards, 

 -—the hind-leg nearly to the ear. 



The ground-colour is bluish-green, the upper parts being reticu- 

 lated with black ; whitish spots appear on the hind-legs ; the lower 

 side white. 



inches, lines. 



Total length 4 3 



Distance between the extremity of the snout and 



the tympanum 0 5 



Distance between the tympanum and the vent . . 1 3 



Length of the tail 2 7 



of the fore-leg 0 7i 



of the hind-leg 1 0| 



Haligenes, Gthr. 



Body compressed, rather elevated, covered with cycloid scales of 

 moderate size ; cheeks and opercles scaly ; lateral line interrupted. 

 One dorsal with fourteen spines ; the anal with three. Each jaw 

 with a series of teeth, compressed and notched at the top ; a second 

 series of smaller ones in the upper jaw, separated from the anterior 

 by a groove ; no teeth on the palate. The lower pharyngeal bone 

 triangular, with cardiform teeth. Branchiostegals five ; air-bladder 

 present. 



This form belongs to the family Chromidce, and may be distin- 

 guished from Chromis and Hemichromis, Peters, by the teeth, from 

 Sarotherodon, Riipp., by the scaliness of the opercles and by the 

 teeth, from Glyphisodo7i by the lateral line, &c. 



Haligenes tristrami, Gthr. (PL IX. fig. B.) 



Diagnosis. — B. 5. D. j|. A. ~. V. 1/5. L. lat. 28. L. trans. 

 3/11. Body greenish, with seven or eight dark vertical bars; an 

 ovate black spot behind the last dorsal spine. 



Hab. Salt Lake and ditches of Tuggurt, Eastern Sahara^ 



Description. — The body is compressed, of semi elliptical form, its 

 greatest height, above the root of the ventral, being 2>\ in the total 

 length. The profile of the nape of the neck is curved, that of the 

 head straight, obliquely descending downwards. The profile of the 

 back is a slight curve, that of the belly nearly straight. The length 

 of the head is 3f in the total. It is covered with scales, except on 

 the snout, and on the prseorbital, and on the prseopercular margin. 

 The snout is rather short, somewhat longer than the diameter of the 

 eye. The mouth is slightly oblique, with the jaws equal anteriorly, 

 and with the upper maxillary reaching to the vertical from the anterior 

 margin of the eye. There is one nostril only on each side, situated 

 midway between the eye and the extremity of the snout. The eye 

 is placed high up the side, but it does not interfere with the upper 



