24G ZOOLOGY. 



ALOSA MUSICA, Girard. 

 Pi.\TF. XXXI, Figs. 1—4. 



Spec. char. Body subfusiform, elongated, compressed, and tajDcring posteriorly. Origin of 

 ventrals opposite the middle region of dorsal. Posterior extremity of upper maxillary reaching 

 the vertical of anterior rim of pupil. Lower jaw longest. Back bluish ; sides silvery. A 

 series from nine to eleven roundish spots along the sides. 



Syn. Alosa musica, Grd. Proc. Acad. Nat. Sc. Philad. VII, 1854, 199. 



Descr. The body is elongated, subfusiform in its profile, tapering considerably on the 

 peduncle of the tail. The greatest depth, measured immediately in advance of the anterior 

 margin of the dorsal fin, is a little less than the fifth of the entire length, whilst the least depth, 

 near the base of the caudal, is about the third of the former. The greatest thickness, on the 

 thoracic region, is equal to half the greatest depth. The dorsal and abdominal outlines are 

 very regular and but moderately convex. The head, which forms about the fourth of the total 

 length, continues uniformly towards the outlines just mentioned, in the shape of an acute 

 triangle, rounded upon its summit, where the mouth opens, with a lower jaw somewhat longer 

 than the upper ; the latter is but slightly notched. Its upper surface is flattened. The upper 

 maxillary is broadly dilated, and rounded posterioidy, where it reaches a vertical line which 

 would intersect the anterior rim of the pupil. The nostrils are small, and nearer to the tip of 

 upper jaw than to the anterior rim of the eye. The anterior one is rounded, whilst the poste- 

 rior one is subcrescentic and convex posteriorly. The eye is large and circular, and ajiproxi- 

 mates the ujjper profile of the head ; its diameter being contained about four times and a half 

 in the length of the side of the head. The opercular apparatus is posteriorly subtruncated and 

 undulated ; the upper part of the opercle exhibits small, radiating grooves, whilst oblique and 

 rectilinear strife are observed along the anterior half of its lower part. The other opercular 

 pieces are smooth. The branchiostegals, six in number, are very thin and flattened; the inner- 

 most is particularly expanded and notched upon its posterior and external margin, correspond- 

 ing to a similar emargination of the inferior edge of the opercular apparatus at the junction of 

 the sub and interopercles. 



The anterior margin of the dorsal fin is nearer to tlie tip of snout than to the base of caudal 

 fin. It is higher anteriorly than long, with its first tliree rays rudimentary and simple, like 

 the fourth, which is the highest ; the posterior margin of that fin is comparatively low, having 

 but the third of the height of the anterior margin. Its upper margin is concave. The central 

 rays are bifurcated twice, the first subdivision taking place upon the posterior third of their 

 length. The anal is situated far back, is very low, and subconcave exteriorly ; its base is a 

 little longer than that of the dorsal, and its anterior margin less deep than half the height of 

 the anterior margin of the dorsal. The second, third, and fourth rays are the longest, and 

 remain simjjle, as well as the first. The central rays subdivide but once. The caudal fin is 

 deeply forked, and its lobes are acute, constituting about the sixth of the total length, its cen- 

 tral rays bifurcating three times upon their length. The origin of the ventrals is situated 

 opposite the middle of length of dorsal. These fins are of moderate development, and poste- 

 riorly subtruncated, their tips projecting slightly beyond the longest rays of the dorsal. The 

 pectorals are well developed, of a rather slender appearance when contracted, and very broad 

 exteriorly when expanded. They are inserted immediately beneath the subopercle ; their 

 external margin is twice and a half as long as the internal, their posterior edge being rounded 

 and subconcave. The central rays bifurcate three times, as do also those of the ventral fins. 



Br. VI : D 19 -I- 1 ; A 16 -t- 1 ; C 5. I. 9. 8. I. 4 ; V 8 ; P 17. 



The anterior ray of both ventral and pectoral fins is simple, but articulated. 



