No. 7.] WH1TEAVES — JURASSIC FOSSILS. 401 



dium or beak of the dorsal valve) ; obliquely and concavely 

 truncate ; foramen rather large ; lateral ridges distinct. Dorsal 

 valve with an impressed line or groove in the centre, which ex- 

 tends nearly half-way to the front margin, and indicates the 

 position and shape of the mesial septum ; on either side of this 

 there is a single (?) divergent muscular scar, of nearly the same 

 length. The shape of the scars is subspathulate or elliptic-ovate, 

 but they each commence as a simple impressed line. Surface 

 marked with coarse, distant, concentric striae or plications. 



Sigutlat Lake and Iltasyouco River, abundant. 



The only Terebratula yet recorded from rocks which are 

 known to be of Jurassic age in North America, is described and 

 figured by Meek, though without any specific name, in the first 

 volume of the Palaeontology of California. It was obtained on 

 the western slope of the Sierra Nevada, and appears to be dis- 

 tinct from the present species, as it (the Nevada shell) has a 

 more globose form and a short mesial fold and sinus. An ovate, 

 elongated Terebratula occurs in the coal-bearing rocks of the 

 Queen Charlotte Islands, in beds which may be Jurassic, but 

 young specimens from the last mentioned locality are much wider 

 than long, which is not the case with any of those collected by 

 Mr. Dawson. In the absence of any knowledge of the test of 

 this species, it is very difficult, and indeed almost impracticable 

 to separate it by any valid character from some European Tere- 

 bratulae, such as T. ovoides, Sowerby, and T. punctata, Sowerby 

 (including T. subpunctata) as described and figured by David- 

 Bon ; more especially from the first of these. 



2. Gryphma calceola, var Nebrascensis, Meek & Hayden. 

 Iltasyouco River, one typical and characteristic convex valve, 

 ■with the test preserved, showing both the internal and external 

 surface markings ; also an exfoliated specimen with both valves 

 in situ, and a few casts. 



3. Camptonectes (?) extenuatus, Meek & Hayden. A cast of 

 the convex valve of a small Pecten from the Iltasyouco River, 

 precisely similar to the specimen figured under the above name 

 on Plate III. (fig. 6), of the " Palaeontology of the Upper Mis- 

 souri." The surface markings of C. extenuatus are unknown, 

 as is also the shape of its ears, and its generic position too is 

 quite problematical, though its aspect is more that of a Syncy- 

 clonema than of a Camptonectes, Casts of the flat valve of a 

 thin compressed Pecten are rather frequent in the Iltasyouco 



