DESCRIPTIONS OF UPPER JURA FOSSILS BELEMNOIDS. 427 



^ ^Icostephanus lindgreni, n. s. 



Loc, near Colfax, Placer county, California. 



The specimen representing this species is unluckily so much altered 

 by compression that some of its characteristics become doubtful. The 

 tubercular aspect of certain of the lateral costse is probably due to 

 flexures, occasioned by pressure in the direction of the dorso-ventral 

 diameters of the whorl. The lateral costae are divided upon the sides 

 into numerous smaller costae, which cross the abdomen continuously ; 

 that is to say, the costae have the aspect of a species of Olcostephanus of 

 the Virgatus group of that genus, which has been so finely described by 

 Michalski * in the Russian fauna of the Upper Jura. So much depends 

 upon the development of the young in this genus that I cannot compare 

 it with any species yet described. That it is not probably identical with 

 the adult stage of any one described by Michalski seems to be plain even 

 in this imperfect specimen. 



- (Ecotraustes denticulata, n. s. 

 Loc, Stanislaus river, Bostwicks bar, near Reynolds ferry. 



This is a species belonging to the smooth-whorled, denticulated section 

 of the genus which occurs in the Upper Jura. The specimens, although 

 only fragments considerably compressed, shoAV the denticulations, the 

 aperture in part and the sutures. The characteristics of all of these indi- 

 cate plainly that it is a species of (Ecotraustes, allied to such forms as 

 (Ecotraustes (Ammonites) lochensis, sp. Oppel., of the Oxfordian. It may 

 be that its nearest congener is in the Solenhofen slates, but in order to 

 make such a close diagnosis better specimens must be procured.f 



The sutures have a short abdominal lobe, with large siphonal saddles, 

 large first lateral lobes, with three long, slender terminal lobes and other 

 parts of the outline, as in the section of the genus to which it is referred. 

 This genus is sometimes confused with Amaltheus of the Lower Jura, but 

 the resemblances are very slight and do not need discussion. 



BELEMNOIDS. 



Belemnites pacificus. 



Belemnites pacificus, Gabb. Proc. Cal. Acad. Sci., 1864, p. 173 ; Geol. Cal., 



vol. i, p. 482. 

 Loc, Mariposa county and American canyon near Greenwood, California 



In the remarks below on this species I have joined what I really 

 think are four species ; one short one from Mariposa county, the true 



* Die Ammoniten d. unt. Wolga-stufe. 



t A compressed fragment of a specimen from Texas ranch, Calaveras county, now in collection 

 of the National Museum at Washington, is apparently a species of (Ecotraustes and may be iden- 

 tical with this, but the condition of the specimen did not permit exact comparison. 



LX— Bull. Geol. Soc. Am., Vol. 5, 1893. 



