236 ZOOLOGY. 



PERCILIA GILLISSII, Girard. 

 Plate XXIX, Figs. 5—9. 



Spec. char. Snout sliort and rounded ; mouth small ; posterior extremity of ujiper maxillary 

 corresponding to the vertical of the anterior rim of the eye. A few minute spines upon the 

 angle of preopercle. Scales large, conspicuously ciliated posteriorly. Ground-color light red- 

 dish, or reddish brown, maculated with black. 



Syn. Percilia Gillissii, Grd. Proc. Acad. Nat. Sc. Philad. VII, 1854, 19T. 



Descr. This is a comparatively small species, and in all probability the specimens before us 

 are full-grown ones. The largest we have seen measure about three inches and a half in total 

 length, of which the head constitutes the fourth part. The dorsal and abdominal oiitlines are 

 convex, giving to the whole profile a fusiform aspect. The peduncle of the tail is moderately 

 developed, and rather narrow. The greatest depth, measured in advance of the first dorsal, is 

 contained three times in the length, the caudal fin excluded; the least depth, taken on the 

 pedi;ncle of the tail, enters seven times in the same dimension. The greatest thickness equals 

 half the greatest depth. The body, therefore, is much compressed. The occipital region is 

 slightly depressed. The snout is short and rounded, and the upper jaw, which is slightly pro- 

 tractile, overlaps a little the lower one. The mouth is quite small, the posterior extremity of 

 the upper maxillary extending to a vertical line, which would pass immediately in advance of 

 the anterior rim of the orbit. The maxillary teeth are small, subcyliudrical, slightly tapering 

 towards their point, and disposed upon several rows. The front of the vomer is provided with 

 a subtransverse narrow band of card-like teeth, and not very conspicuous. The palatine bones 

 are smooth. The pharyngobranchials are well developed, and densely covered with minute 

 prickles. The tongue is smooth, small, semi-elliptical in shape, and very much flattened, 

 mayhap more swollen in a living state. The eye is of medium size, and subcircular ; its hori- 

 zontal diameter being contained nearly four times and a half in the length of the side of the 

 head. The preopercle exhibits but a few minute spines upon its limb ; the oiDcrcle has no 

 spine at all ; and the inferior edge of both the sub and interopercle is entire, or else not cre- 

 nated. The gill openings are continxious under the throat, but there is a membranous expan- 

 sion between the adjoining branchiostegals, thus filling up a space which is open in the species 

 of Percicldliys, above described. The branchiostegals are five or six in number, flattened, and 

 recurved. The suprascapular is not visible externally ; the coracoid expands much less above 

 the base of pectorals than in Percichthys ; and, moreover, these bones are neither provided 

 with spines nor crenated upon their edges. 



The dorsal fins are similar in general appearance to those of the foregoing percoids ; the 

 membrane which unites the spines is deeply emarginated ; but the two intermediate spines be- 

 tween these two fins do not exist in this species. There are, consequently, nine dorsal spiny 

 rays. The ninth, which is closely connected with the posterior fin, is the smallest of all ; the 

 eighth comes next, and is but very little higher than the latter ; the others increase in height, 

 as follows : first, seventh, sixth, second, fifth, third, and fourth. There are instances where 

 the third is slightly higher than the fourth, as is also the case in Percichtlnjs cMleiisis. The 

 second dorsal is not quite as high as the first, though a little liigher than its own base ; on the 

 other hand, the base of the first dorsal is longer than its height. The middle rays bifurcate 

 twice upon their length, and their tips extend a little further backwards than those of the anal. 

 The latter is preceded by three spines similar to those in Percichthys cliUensis and allied species. 

 A few of the central soft rays exhibit traces of a bifurcation of the third order ; the others 

 are as in the second dorsal, the external margin of which fin is rounded or subconvex, as is 

 the case in the anal. The caudal is broad and subcrescentic upon its posterior edge, the cen- 

 tral rays bifurcating three times. The insertion of ventrals is situated behind the base of the 



