C. labtatus must be rather rare as but a single 

 specimen has yet been observed ; it was taken at 

 Stockton, was seventeen and a half inches in 

 length. It was brought to market in company 

 with a number of C. ocadentalis, from which it 

 was not distinguished by the fisherman who call 

 them both Sucker. 



We knew in California, previous to the discov- 

 ery of this species, but one representative of the 

 genus Catostomus, C. occidental is, Ay res. By a 

 somewhat singular coincidence this latter had 

 been described by Prof. Aggassiz (Am. Jour. 

 Sc. and Arts, Vol. If), p. 94,) and by myself 

 (Proc. Cal. Ac. Nat. Sc. Yov. l,p. 18, under 

 the same specific name, at almost the same time, 

 but the reading of my paper and the publication 

 of our Proceedings have priority by a lew days. 

 Prof. Agassiz' account of course did not reach us 

 til! several weeks later. 



From C. occidental it, the present species is 

 distinguished by the following characters— the 

 head, anterior to the eyes, is more elongated ; the 

 centre of the eye is decidedly nearer to the lower 

 angle of the subopercle than to the anterior edge 

 of the upper lip ; the mouth is larger, the lips 

 thicker ; the opercle and subopercle are smaller ; 

 the dorsal fin is situated further back, and is 

 smaller, its length being less than one seventh 01 

 the length to the tip of the central caudal rays ; 

 the pectorals are larger ; and tht- anal is much 

 more developed. 



From C. communis it differs in the greater 

 length of the head, the larger mouth, the thicker 

 lips, the form of the dorsal, and the greater de- 

 velopment of the anal; and from C. Bostoniensis 

 in nearly the same points. 



To Lesuenr's C. aurcolus it has much resem- 

 blance, but from that it is now generically sepa- 

 rated, as in the recent revision of the old genus 

 Catostomus by Prof. Agassiz, atoeolus is inclu- 

 ded in the genus Ptychostomus. 



In a paper read by me before the Academy 

 aome months since, the remark was made that fur- 

 ther investigations in our Californian fauna would 

 probably show a necessity for many modifications 

 among existing genera. In the present specie.?. 

 we have a partial illustration of the truth of this. 

 In the revision of this group of fishes already 

 mentioned, Prof. Agassiz after much study has 

 set forth the characters which in his judgment 

 should indicate generic divisions, attaching much 

 (though not undue) importance to the inferior 

 pharyngeal bones and the teeth upon them. In 

 the arrangement thus proposed by him, the spe- 

 cies now under consideration belongs evidently to 

 Catostomus proper. And yet we find the pharyn- 

 geal teeth (but not the pharyngeal bones them- 

 3elves) much more nearly corresponding to those 

 of Ptychostomus. They increase in a very even 

 manner from above downward, so that those of 

 the middle of the arch are not "aJreadv of the 



same cast as those of the lower part of the comb,' ' 

 in fact they do not assume that cast till quite 

 near the lower part. We find "the inner edge of 

 the lower ones square," while in the middle and 

 upper ones the inner margin rises into a rather 

 sharp cusp. Still the body of the bone ia that 

 of Catostomus and we have thus a blending of 

 the characters of the two genera. 



Without question other types of this group of 

 fishes will yet be discovered on this side of the 

 mountains. Quite a remarkable representative 

 of the Chondrostomi was fouud by the U. S. Ex- 

 ploring Expedition, under Capt. Wilkes in the 

 Columbia River. It is Acrocheibts alviacms, 

 Agass. and Pick. 



Mabch, 12, lfctta. 



Dr. Ay res in the chair. 



Dr. Antisell was elected a Corresponding 

 Member, and Mr. Julius Frofbel a Resident 

 Member. 



On motion it was ordered 



That copies of the proceedings of the Acade- 

 my be furnished to the San Francisco Journal, 

 to be published in the German language. 



Dr. Kellogg exhibited a drawing and speci- 

 mens of Arobis llepharophjlla, or CaL Purple 

 Rock-cress. 



This beautiful purple flowered Rock-cress, as 

 its common name implies, is only found in rocky 

 localities. It has been supposed to be from the 

 interior of this State, but it is found abundantly 

 on the rocky peaks of mountains and high hills 

 iu this vicinity, and along the coast; this habit of 

 growing on high hills has also obtained for it the 

 names of Purple Alpine Wall Flower, &c, 



It is a perennial cruciferous plant: 4 to 6 la- 

 ches high, the flower stem rising from a cluster 

 of radical leaves, obovate-spatulate; those of the 

 stem oblong, sessile, all toothed and naked, ex- 

 cept the margins, which are ciliate with simple 

 or forked white hairs; the hairs on the calyx Btel- 

 late, petals purple, obovate, crenate on slender 

 claws &c. 



For ornamental purposes this plant is snperior 

 to many of our cultivated species. 



Dr. Ayres presented the following description 

 of a new i«hthyic type, together with a specimen 

 of the species described. 



Mtlophakodon -jtoflusTus, Ayr**. 

 Form, elongated, fusiform, compressed; »«&• 

 tral outline more arched than the dorsal ; dorwl 

 outline aswnding without curvature from tim 



«.— , 



