250 Transactions. — Zoology. 



falls in a rapid slope to near the lower edge of sides, whence 

 it again rises slightly and runs on to tail, being well marked 

 for some distance along the caudal-fin membrane. 



Fin-ray formulce : D., 12 ; anal, 11 ; caudal, 10. Head is 

 to body and tail as 4 is to 15. Head is to total length (to 

 extreme margin of caudal) as 5 is to 21. 



Colour of back and upper sides a rich plumbeous-green 

 with silky reflections ; sides of bright metallic silvery lustre ; 

 anal, dorsal, and caudal fins dull-yellow, darkening more or 

 less to reddish-orange on some of the rays, margined with 

 black, but terminating on their extreme borders with more or 

 less opaque milk-white. 



The mouth was rather larger and teeth stronger than those 

 generally appertaining to the genus, that portion of the 

 upper teeth nearest the division between same being distinctly 

 thickened and rounded. 



Total length of fish (extremity of snout to margin of 

 caudal), ll-25in. Length of fish from extremity of snout to 

 origin of caudal, 9-4in. Length from extremity of snout to 

 gill-opening, 2-6in. Diameter of orbit, 0-6in. Length, ex- 

 tremity of snout to vertical from origin of dorsal fin, 6'9in. 

 Greatest depth of body with stomach in normal condition, 

 3-5in. Median heights of free portions of dorsal, anal, and 

 caudal fins, l-3in. 



The length of the head equals the vertical depth between 

 the fin-ray origin of the dorsal and anal fins, and is much 

 less than the full expanded width of the caudal fin. The 

 shortness of the head as compared with the distance from 

 same to dorsal, or with the head and body length or total 

 length, is a considerable specific feature in distinguishing this 

 from others so far described. The anal orifice is placed some 

 distance in front of the origin of anal fin. 



Decomposition proceeded very quickly with this fish after 

 it was obtained, although it was perfectly fresh when brought 

 to me, the skin being very tender. Perhaps this was hastened 

 by the birds breaking into the fish through the gill-openings. 

 Further decomposition was checked by immersion in strong 

 alcohol, but this had the effect of considerably shrinking 

 and distorting the specimen. It tightened up the peculiar 

 mosaic-like development of the abdomen, causing the little 

 spines to be almost completely hidden. 



