18 ME. G. A. BOULENGEE ON A COLLECTION 



19. Tropheus mooeii, sp. n. (Plate V. fig. 2.) 



Teeth minute, those of the outer series tipped with brown and numbering about 50. 

 Depth of body 2| to 2§ times in total length, length of head 3J to 3-1. Snout 

 descending in a strong curve, as long as or a little longer than the diameter of the eye. 

 which is 3| to 4 times in length of head, and equals § to f interorbital width ; mouth 

 extending to below anterior border of eye ; 4 series of scales on the cheek ; large scales 

 on the opercle. Gill-rakers short, 11 or 12 on lower part of anterior arch. Dorsal 

 XXI 5-6 ; spines increasing in length to the sixth, which measures not quite half 

 length of head ; longest soft rays § to f length of head. Pectoral as long as head. 

 Ventral produced into a short filament, reaching beyond origin of anal. Anal VI 5-6 : 

 spines increasing in length to the last, which slightly exceeds longest dorsal. Caudal 

 slightly notched. Caudal peduncle as long as deep. Scales 30-32^; lat. 1. jx^r"> 

 Dark brown ; a large bluish-white blotch on each side ; belly reddish brown ; fins 

 blackish. 



Total length 110 millim. 



Five specimens from Kinyamkolo. 



The occipital crest is very strong and the parietal crests are produced on the frontals. 

 The insertion of the ribs is as described in the preceding genera Telmatocliromis and 

 Eretmodus. 



The mouth and pharynx of one of the specimens contains four eggs of very large 

 size, the vitelline sphere measuring 4 millimetres in diameter, with an embryo in an 

 advanced stage of development. The egg of the Fifteen-spined Stickleback ( Gasterosteus 

 spinachia), hitherto regarded as the largest Teleostean egg in proportion to the size 

 of the animal, measures only 3 millimetres in diameter \ Besides the Siluroids of 

 the genera Arius and Galeichthys, which have very large eggs, at least two species 

 of Tilapiayvere known to give shelter to their eggs in the manner noticed above, viz . 

 T. simonis Gthr. (Chromis paterfamilias Lortet), as observed by Prof. Lortet in 

 Lake Tiberias, and T. nilotica Cuv., as noticed by me in a specimen collected by Canon 

 Tristram in the same lake. But these eggs, produced by fishes of the size of our 

 common Perch, are very numerous, and measure only about 2 millim. in diameter. It 

 has besides been observed in these Tilapice, as well as in the Siluroids, that the function 

 of protecting the eggs devolves on the male sex, while, to my surprise, the 

 Tanganyika fish proved on autopsy to be a female. Whether this is constantly so, or 

 whether either parent takes to the nursing duties, remains to be ascertained by 

 examination of a larger number of specimens. I am all the more disposed to think 

 the latter possibility will be confirmed, from the fact that a specimen of Tilapia nilotica 



1 The absolutely largest known Teleostean egg is that of the Siluroid Arius commersonii, which measures 17 

 millim. in diameter. The size of the Arius-egg is much underrated by Giinther (' Study of Pishes,' p. 160) and 

 by Mcintosh and Masterman ('British Marine Food Eishes,' p. 12), who ascribe to it a maximum of 10 millim 



