907 



1(1 tli;il, wlu'i-o M c-liiiniic nf urowili is clearly dcliui'd i abuvn tal>lc, the hhisikiir, howcvci', often t'ollo\\- a dil 



f'erfiit rule froiii the fctsikar. and conso(:|ucntlv, wlieii 

 the former become maiioceiitrous, or the latter pycno- 

 ceiitrous. the general rule foi- the sexual difference is 

 conunoidy reversed, a circumstance whicli most readily 



in tclldcnc^^ the fetsik {/.(irdrctiis), at the same size as 

 ilic lilasik, has attained a more ad\anccd development. 

 The sexual differences show that in the males the 

 length of the alidominal |)art is generally less than in 

 the females, the anal tin thus beginning comijai-atixely i suggests the presence of in'bridism". 

 farther forward, and the snout broader but longer, the [ Guided l)y the alterations of development and the 



males being thus ranged as representatives (jf the i dift'erenees of sex included in the preceding table, we 

 earliest developmental stages of the type. In the dif- I maA' easily explain the form-series, as it apjiears in 

 ferences of sex, which may easih' be traced in the | the following talile of averages: 



Xunibcr of spefimcns 



Length of the botlv expressed in 



Number of gill-rnkers on the first left brauehinl p.rch 



Ltnath of the head in % uf the len'ilh of the bod 



■educed 

 ' -rimee between the dorsal fin and the tip of 

 'lie snout 



of the dorsal fin 



Height „ 



Length of the pectoral fin: 



Preubduminal length 



Distanee between the ventral tins and the tip nf 



the snniit 



Length of the ventral fins 



Postabdominal length 



DiataDce between the anal fin and the tip of 



the snont 



Itase of the anal fiu 



Height „ 



Dorsal margin of the peduncle of the tail 



length ,. ., „ „ ,. ., 



Ventral margin .. .. „ ,, ., „ 



Leist depth ., .. .. ,. .. „ 



Lerntth uf the middle catidal rays 



longest rays in the upper caudal lobe 



snout 



Longitudinal diameter of the ey 



Vertical , , 



Breadth of the snout at the rostral protuberances.. „ 



Depth , , ., . ,, 



Breadth of the forehead at the middle of the eyes.. ., 

 length of the ma.villaries „ 



„ ., ,, lower jaw _ „ 



„ ., „ snboperculu 



Vertical diameter of the eyes in % of the length uf the head red 



Deptbofthesnout at the rostral protuberances ., .. „ ., ., .. ., 

 length of the maxillaries..... , ,, „ „ „ „ „ 



•, „ ,, lower jaw ,, „ ,, „ ,, „ „ „ 



Uut depth of the peduncle of the tail „ „ „ ,, ., ,, „ „ 



Breadth of the inajillaries in % of their length 



Depth of the snout at the rostral protuberances in % of its breadth at the same point. 



" M ,. , ., .. ., ,. the length of the maxillarics. 



length of the head reduced in % of the distance between the dorsal fin and the 



'ip of the snout 



" S.MrrT, 1. c, pp. -281 



