26 Bulletin 33 26 



the adult. 



Our collection of this species consists of a series of four spec- 

 imens, which range in length, 22 mm, 87 mm, 1 18 mm and 123 mm 

 respectively ; were it not for this series showing the gradation in 

 size and umbonal ridge one would not be inclined to identify the 

 two extremes as the same species. 



This form resemble Thyasira biseda (Conrad) from the Mio- 

 cene of the West Coast of North America. The Pacific species, 

 however, does not reach such a ponderous size. No species of 

 this genus has been reported from the East Coast American Ter- 

 tiaries. This would seem to give our fauna a closer affinit^^ with 

 the West Coast forms of the Middle Tertiary Stages. 



Types. — Pal. Museum, Cornell Univ. 



Age. — Probably Middle Tertiary. 



Locality. — "One mile west of Godineau River, on the shore 

 of the Gulf of Paria, about midway between San Fernando and 

 La Brea, Trinidad." 



Collected by A. C. Veatch in 191 2, then of the General As- 

 phalt Companj' of Philadelphia. - 



SOLARIELLA S. Wood 



Solariella gotlitieauensis, n. sp., PI. 3. Figs. 17, 18. 



Description. — Size and shape of shell as indicated hy the fig- 

 ures ; bod}^ whorl ornamented with three, pronounced, equally 

 distant carinae ; all of the whorls are carinated but with each suc- 

 ceeding volution the carination is diminished hy one ; as the car- 

 inae extend to the apex they become more and more crenulated ; 

 in the concave area between the shoulder and the suture is a 

 smaller keel very strongly crenulated, producing a nodose condi- 

 tion ; these are caused by the intersection of the keels with 

 prominent, radiating ribs which extend from the suture to the 

 shoulder carina, traces of these ribs maj' be seen on the lower 

 portion of the bod}- whorl ; they have interspaces of about three 

 times the width of a rib ; aperture wide and flaring, ^this flare ex- 

 tending conspicuously out from the basal margin ; two or three 

 additional revoling ridges extend on the bod}" whorl below the 



