1883.] 327 [Hyatt. 



which is a discoidal shell. Type, Munst. parallelum, sp. Hall, 

 Mus. Geol. Surv. Albany. 



G-astrioceras, 1 nobis, includes species with open umbilici and 

 whorls in section semilunar or trapezoidal. The abdomen is wider 

 than the dorsum and the sides often costated. The larvae always 

 have whorls semilunar in section, and similar in form and sutures 

 to the larvae of Brancoceras during the stage before the genera- 

 tion of the siphonal saddles. The siphonal saddle is developed as 

 in the Primordialidae, but is not usually so large or broad as de- 

 monstrated by Branco and confirmed by our own observations. 

 The sutures at earlier stages and the whorls have the usual simil- 

 arity to those of the adults of Anarcestes. The adolescent and 

 adult stages have deep, straight-sided ventral lobes and siphonal 

 saddles which are often more or less prominent and angular. The 

 first pair or primitive saddles are on the venter and often spatu- 

 late making the sutures similar to those of Munsteroceras, while 

 the general aspect of the shells is representative of Glyphioceras. 

 The magnosellarian saddles are divided at the shoulders of the 

 whorls with acute lobes, and internally are flanked by saddles ris- 

 ing rapidly to the zone of impression as in Munsteroceras. Gast. 

 (Gon.) Listeri, sp. Phill. Geol. York. pi. 20, fig. 1, of the Carbon- 

 iferous and Marianus, ibid, pi. 27, fig 2, and Jossae, sp. M. V. K. 

 Russ. and Ural Mts. pi. 26, fig. 2, both from the Dyas are 

 European examples of this genus, and in this country we find 

 Gast. (Gon.) Kingii, sp. H. W., U. S. Geol. Surv. Expl. 40th Parall. 

 Vol. 4, pi. 6, fig. 8, and (Gon.) globulosus, sp. M. W., Geol. Surv. 

 111., Vol. 2, pi. 30, fig. 2. 



Paralegoceras, 2 nobis, is similar to Gastrioceras in its sutures, 

 but the whorls are compressed, and the sides smooth in the cast. 

 The sutures are similar also to our genus Schistoceras, but the 

 broad, shallow, angular second lobes, and the peculiar internal 

 saddles show closer affinities for Gastrioceras and Munsteroceras. 

 It is apparently a compressed Carboniferous form directly con- 

 nected with Gastrioceras. The only species known to us is the 

 Paral. (Gon.) Iowense, M. et W. Geol. Ill, Vol. 2, pi. 30, fig. 3, 

 from the coal measures. 



1 TcLTTpis, a pot-belly. 2 IlapaXe-yw, I lie by the side of. 



