29 



ding the ligament, lateral ridge of the shell form- 

 ing the chord of a circle equal to ] 05' , epidermis 



rough, finely wrinkled anteriorly, very dark brown, 

 semi-opaque, surface of the shell often very much 

 denuded. 



Interior of the Valves. Muscular cicatrices 

 two. anterior deep ami at times granulated, pos- 

 terior confluent, the cicatrices usually with raised 

 tumid edges; pallia! line rather deep in old speci- 

 mens, rather indistinct posteriorly in young' shells, 

 nacre opaque reddish brown, pearly, annual lines 

 imperceptible within, but distinct externally, in- 

 ternal cavity deep, cavity of the umbo deep ; 

 Length three and one tenth inches, Breadth one 

 and four tenths. Diameter one and two tenths. 



The habitat of this .Shell is the Sacramento 

 and San Joaquin Rivers. I have not found it at 

 any point north of the confluence of the Feather 

 u ith the former stream. The shell is not plenti- 

 ful as one only was obtained during three days 

 dredging ; it is difficult to obtain good specimens, 

 or even any considerable number, from the fact 

 that the Indians place a high value on them, their 

 use being the manufacture of ornaments for their 

 persons. 



I have some hesitancy in placing this shell with 

 the genus Anodon, since there is in some 

 specimens, the semblance of a rudimentary tooth. 

 In the majority of shells which have come under 

 my observation, this characteristic is wanting or 

 at least 80 obscurely denned as to render it ex- 

 tremely difficult to determine the point with any 

 degree of certainty. 1 have never seen the ani- 

 mal Jjut once, and that was in such a state of 

 decomposition as to render any diagnosis from 

 this source of no value. I have, from these cir- 

 cumstances placed this shell in the genus Anodon 

 until such time as there are more evidences for 

 its removal than are now in our possession. A spe- 

 cimen of this species is in the cabinet of Col. L. 

 Ransom, from the upper San Joaquin, which 

 measures three and eight tenths inches in length 

 and one and seven tenths in height — it is the lar- 

 gest that has yet been taken in our waters. 



Auodonla triangularis, Trask. — Shell, thin, con- 

 tour nearly triangular, inequi-lateral,equi-valved, 

 compressed ; anterior margin truncated ; ventral 

 margin nearly straight for the central half of its 

 length ; valves slightly compressed near the ven- 

 tral margin producing a flattened elevation on 

 the inner disks; posterior extremity obtusely 

 rounded ; dorsal margin elevated into a high con- 

 nate wing; beaks nearly obsolete; epidermis 

 greenish in young and dark brown or nearly 

 black in old specimens ; annual lines somewlial 

 prominent externally, raised on the inner disks ; 

 pallia] line entire ; cavity of the valves shallow ; 

 nacre white, slightly iridescent; dorsal ligament 

 strong ; valves closed. Length three and three 

 tenths, Height two and two tenths, Diameter 

 seven tenths. 



The habital of this Shell is the Idacramento 

 River, and it has qo1 to my knowledge been found 

 above the American Fork. It is seldom seen by 

 the fishermen engaged on thai stream, notwith- 

 standing high prices have been ottered for them ; 

 within is months I have procured three speci- 

 mens only. The outline of this sheh alone would 

 separate it from the lake specimens, which are 

 found in great abundance. 



Anodonta rotundovata,Tra8k. — Sliell inequilat- 

 eral, compressed; umbo rather Bat; dorsal line 

 straight; projection of the epidermis above the 



dorsal line arcuate, horny and brittle; anterior 

 margin rounded ; ventral margin regularly arch- 

 ed and smooth ; dorsal margin elevated into a 

 high connate wing; darkish brown colored line 

 surrounding all the margins ; muscular impression 

 rather indistinct; posterior cicatrice confluent ; 

 pallia! line small but easily perceptible, conform- 

 ing to the marginal border ; epidermis yellowish 

 brown, polished, finely corrugated near the mar- 

 gins and becoming darker ; substance of shell 

 thin ; annual lines transverse, elevated exteriorly 

 and perceptible on the disk ; cavity of the beak 

 shoal ; nacre bluish white, pearly, at times mot- 

 tled with yeilowish spots. Length three and six 

 tenths inches. Height one and nine tenths, Diam- 

 eter seven tent lis. 



This sliell is found in the lagoons of the Sacra- 

 mento Valley; but has not to my knowledge 

 been taken in the river. The plates were drawn 

 from an adult specimen; it differs from the pre- 

 ceding species in its general contour,in being more 

 expanded between the dorsal line and ventral 

 margins.and in the much greater acuteness of that 

 line, with the projection of the epidermis beyond, 

 as delineated in the figure. The arched form of 

 the ventral margin in this specimen, and the 

 roundness of the anterior, compared with those 

 of the A. triangularis, will separate it from that 

 shell. 



Dr. Window, exhibited two embryonic speci- 

 mens of a species of Shark-Ray, inclosed in the 

 egg-case. 



Dr. H. Gibbons exhibited specimens of the 

 Redwood and the Mammoth Tree, with the cones 

 of both, showing the analogy between them, and 

 the propriety of placing them in the same Genus 

 viz: Taocodium. The Genus Wellingtoiiia, which 

 Lindley had framed for the gigantic tree of Cal- 

 ifornia, was at best, named in bad taste. If the 

 name of a hero, unknown to science, were at all 

 appropriate foragenusofplanls.au American 

 hero, might easily have been found, to give a 

 name to the giant of the American forest. Rut 

 there is not likely to be any difficulty about the 

 name, as Dr. Torrey and other botanists, both at 



