1914] 



English : Agasoma-like Gastropods 



24!) 



on the lower row, formed where the node is crossed by a coarse spiral 

 line; columella smooth, curved, with heavy, wide callus prominent on 

 posterior part and extending above the suture, in this respect re- 

 sembling the Agasomas; canal curved, medium length, wide, shallow. 



Immature specimens differ considerably from the adult shells. 

 They are more elongated, the canal proportionally longer and less 

 curved, the nodes less prominent or even lacking, the ribbing more 

 regular and the spiral lines fewer in number. 



Height 62 mm., width 45 mm. ; mouth-opening length 54 mm., 

 width 23 mm.; canal width 15 mm., depth 5 mm., length about 15 mm. 



This is a characteristic species of the Turritella ocoyana horizon of 

 the Temblor (Monterey?) formation; Barker's Ranch and Ocoya 

 Creek, Kern County (Cooper; F. M. Anderson): San Luis Obispo 

 County (Cal. Acad. Sci. collection) ; Coalinga (Arnold) ; Santa Cruz 

 Quadrangle (Arnold; Branner) ; a large specimen apparently of 

 this species is present in Fairbanks' collection from the Vaqueros, 

 Turritella inezana horizon, on Vaqueros Creek (Univ. Calif. Coll.) ; 

 ?Topanga Canon, Santa Monica Mountains (Arnold) ; ?Monterey 

 formation, poorly preserved material from the type locality of the 

 Monterey formation has been referred to this species (Martin; Arnold 

 and Hannibal) . 



TROPHOSYC'ON STANFORDENSE (Arnold) 

 Plate 24, figures 2 and 3 



Agasoma stanfordensis Arnold, Proc. U. S. Nat. Mus., vol. 34, p. 384, 

 lil. 35, fig. 5, 1908. 



Neither the type nor material from the type locality was available 

 for comparison, but numerous casts in the University of California 

 collection from the Monterey group of Contra Costa County are re- 

 ferred to this species. It is difficult to make trustworthy comparisons 

 with such material, as the casts represent a combination of exterior 

 and interior characteristics of the shell and are generally somewhat 

 distorted. At present it can not be positively affirmed that this species 

 is different from T. nodiferum. 



The general shape of the shell and character of the decoration is 

 apparently the same as that of T. nodiferum. T. stanfordense appears 

 to differ in having a lower spire, and in having- the columella more 

 sharply excavated below the lower line of angulation. 



