TILAPIA. 189 



greater than prtienrbital depth ; mouth moderate, about f width of head, 

 extending to vertical between nostril and eye ; teeth in 3 series, outer 

 with extremely slender shafts ; 20 to 24 in upper jaw ; 3 series of scales 

 on the cheek, width of scaly part less than diameter of eye. Gill-rakers 

 short, 12 or 13 on lower part of anterior arch. Dorsal XIII 11 ; spines 

 subequal from the fourth, which measures ^ length of head; longest 

 soft rays ^ length of head. Anal III 11 ; third spine ^ length of head. 

 Pectoral | length of head, not reaching origin of anal. Ventral not 



Fig. 122. 



l^ilania alcalicu. 

 Type, xl^ 



reaching vent. Caudal truncate. Caudal peduncle as long as deep. 

 Scales cycloid, 28-30 ^ ; lateral lines ^^^ ; breast and belly naked or 

 covered with minute scales. Brownish above, dirty white beneath ; 

 9 more or less distinct dark cross-bars on the back ; each of the scales 

 on the anterior part of the back with a blue vertical streak. 



Total length 50 millim. 



Volcanic holes near the Nguruman Salt Lake, German East Africa. — 

 Types in Berlin Museum. 

 1-4. Types. Nr. L. Ngaruman. ProL 0. Nenmann (().). 



29. TILAPIA DUBIA. 

 Lonnb. Ann. & Mag. N. H. (7) xiii. 1904, p. 137. 



Depth of body 2 times in total length, length of head 3 times. Snout 

 with straight upper profile, as long as eye, which is 3 times in length of 

 head and 1^ times in interorbital width ; mouth extending to between 

 nostril and eye ; teeth in 3 or 4 series, outer rather large and only 

 slightly notched, about 28 in upper jaw; 3 series of scales on the 

 cheek. Gill-rakers short, 13 or 14 on lower part of anterior arch. 

 Dorsal XVI 13 ; spines subequal from the fifth, about ^ length of head. 

 Anal III 10, third spine nearly as long as but stouter than longest 



