44 



Stales small, elliptical, with the coacentrk lines 

 numerous and crowded ; about one hundred aud 

 forty along the lateral line. Head nak< d. Lat- 

 eral line nearly straight, carving very slightly 

 downward. The first dorsal fiu arises midway 

 between the snoui and the commencement of the 

 accessory ray? of the caudal fin. The first four 

 rays are simple, the first two being very short ; 

 the sixth and seventh are longest, their height 

 equalling the length of the fin, being about one 

 • eighth of the length of the fish. 



The adipose fin is separated from the termina- 

 tion of the first dorsal by a space equal to the 

 distance from the veutrals to the anal, being di- 

 rectly above the termination of the latter fiu. It 

 is narrow ; its height equal to the diameter of 

 the eye. 



The centrals arise very nearly beneath the mid- 

 dle of the first dorsal, being almost midway be- 

 tween the snout and the tip of the central cau- 

 dal rays. They are rounded, their height equal 

 to half the length of the head. At the external 

 base of each is a narrow membranous appendage 

 half as high as the fin. 



The pectorals are somewhat pointed, their 

 height equal to the length of the first dorsal. 



The anal is in form very similar to the first 

 dorsal, but about two thirds as large. The first 

 four rays are simple, the first two being very 

 short ; the fifth and sixth longest. 



The caudal fin is of medium size, coucave, the 

 height of the central rays being about two thirds 

 that of the external. 



Branchial ravs twelve. 



D. 4-11 ; P. 1-14 ; V. 1-10 ; A. 3-10 ; C. 19. 

 with six or seveu accessories. 



This species recalls at once by its characters, 

 the Brook Trout of the Northeastern States the 

 well known Salmo fontinalis, M. and is indeed 

 very closely allied to it. It is one of those known 

 to sportsmen here as Trout and sometimes Moun- 

 Front. The specimens from which this de- 

 scription is drawn were taken a few miles back 

 of Martinez, toward the foot "I Monte Diabolo. 

 They therefore represent the form occurring in 

 that" portion of the State. But from 1 1 i* - accounts 

 which we have received it seems highly probable 

 that under the name Mountain Trout several dis- 

 tinct species are confounded in different parts of 

 California, and the attention of observers, who 

 may have opportunity to examine our mountain 

 streams and lakes. i< therefore requested in regard 

 to this point. The species found on the west of 

 the Contra Costa Mountains, in San Leandro 

 Creek, has in fact been already described, [Salmo 

 indea, Qibl -. I'roc. Cal. Acad. Nat Sciences, 



Vol. l.page ,'Sti ill i- quite distinct from this. 

 S. nvularis is separated from S. fontinalit by 

 the teeth, the proportions of the head, the posi- 

 tion of the dorsal fin. the form of the adipose, 

 the scales, and the eolora. 



The ground colors are quite similar to those of 

 fontinalis, though without the mottlings, but the 

 yellowish circles and vermilion dots are absent. 

 Instead of them we have on the head, aud back, 

 aud upper portion of the sides numerous reddish 

 brown, irregularly circular spots. The dorsal 

 fin bears also several rows of spots forming im- 

 perfect bars ; a few of these are found on the 

 caudal. 



The largest specimen was eight inches in length. 

 They were reported smaller than the average, so 

 that in size also this species comes near to fonti- 

 nalis. We are indebted for them to the kindness 

 of I)r. Winslow. 



Petromyzon ciuatus, — Ayrcs. 



About two months since a small Lamprey was 

 exhibited and described, before the Academy, 

 under the name P. plumbeus (Proc. Cal. Ac. Nat. 

 Sciences. Vol. 1. p. 28,) being the only Californian 

 species at that time known. Within a few days) 

 the specimen herewith presented has been obtain- 

 ed. It is of a type quite distinct from plumbeus, 

 and i- allied very closely indeed to P. American- 

 us, I." S. 



It i> twenty four inches in length, four inches 

 and a half in circumference. 



/'< - hi elongated, subcylindrical anteriorly, com- 

 pressed posteriorly, enlarged over tie- branchial 

 region, head smaller. 



Eyes distant six times their own diameter from 

 the anterior border of the head, nearly circular, 

 only one fourth of an inch in diameter. 



Branchial orifices elliptical, disposed in nearly 

 a straight line on each side, occupying a space 

 about equal to the distance from the anterior one 

 to the front of the head. To the middle of the 

 posterior border of each orifice a short, filiform 

 appendage is attached. 



Mouth circularly continuous. Lips provided 

 in their whole extent with a beautiful ciliary 

 fringe, nearly a tenth of an iuch in height. 



"Tedh" numerous. In the throat are two large 

 plates, placed laterally, which close the entrance 

 almost in the manner of a glottis; they are finely 

 Berrate on their inner border. Immediately be- 

 low these is another, not quite so large, placed 

 transversely, supported on a concealed pedicel, 

 serrate, with its central serrature slightly eleva- 

 ted. Posterior to this and below it is another 

 much stouter and larger, more than half an inch 

 across, placed transversely, with five strong serra- 

 tions. Pacing this, so as to leave the entrance 

 to tla- mouth between them, is another of similar 

 solidity but not quite so broad witli a large, con- 

 j ical prominence on each side and a smaller one in 

 ; the middle. The bases of these two plates are 

 so extended as to form a continuous ring. Ex- 

 ternal to them is a circular row of "teeth" con- 

 Isiating of small, single points in its posterior and 

 anterior portions, while laterally they are imbed- 

 ded plates supporting two, and those opposite 



