182 COLORADO FORMATION AND ITS INVERTEBRATE FAUNA, [bull. 106. 



begiu to develop near the umbilical margin and a larger number of 

 stronger ones form a row near the peripheral margin. Occasionally two 

 costaB unite at one of these outer nodes and again divide on leaving it. 

 As the shell grows the smaller costaB disappear and the larger ones 

 become rounded and less prominent until on the outer whorl of speci- 

 mens an inch and a half in diameter each is represented by two large 

 round nodes. At this stage there are about twice as many nodes in 

 each row of the abdomen as there are in the row near the peripheral mar- 

 gin, so that all the suppressed costaj are apparently still represented 

 by nodes on the abdomen. 



Septa not very complex; the lobes all bipartite and the saddles more 

 or less distinctly [tripartite at their extremities. Abdominal lobe large 

 and rather slender, being nearly twice as long as broad ; first lateral 

 saddle about the size of the abdominal lobe; superior lateral lobe much 

 broader than the first lateral saddle, deeply bifid; inferior lateral lobe 

 and saddle with the forms of those just described but. much smaller. 

 There are one or two very small auxiliary lobes and saddles. 



The type specimens are three young shells and two fragmentary 

 older ones, all of which are septate throughout. The largest specimen 

 gives the following measurements: Diameter, 49 ini "; height of outer 

 volution, 1G"""; breadth of same, 26 ranc . 



This species seems to fall into the genus Aeanlhoceras, as defined in 

 Zittel's Handbuch der Paleontologie, though that genus is made to 

 include a number of groups that are apparently not very closely related. 

 Acanthoeeras angulicostat inn , which may be regarded as the type of the 

 genus, is certainly very different from our form. The latter seems to 

 be related to Amm, colerooncnsis Stoliczka. 1 The suture i.s of the same 

 character and the form as shown in the small specimen (Fig. 4 of same 

 plate) is quite similar, though there is no abdominal keel and thecostae 

 pass entirely across the abdomen. 



Locality and position. — Upper Kanab, Utah, about 350 feet above the 

 base of the Cretaceous section. Another specimen collected from the 

 Austin limestone near New Braunfels, Texas, belongs to the same or a 

 closely related species. 



Genus SOAPHITES Parkinson. 



Scaphites LARViEFORMis Meek and Hayden. 



PI. xliv, Pig. 2. 



Scajridtcs larvceformis Meek and Ilayden, 185G, Proc. Acad. Nat. Sci. Phila., p. 58; 

 Meek, 1876, U. S. Geol. Sur. Terr., vol. IX, p. 418, PL vi, Figs. 6a, b, c. 



Eevised description : 



"Shell small, transversely subovate, compressed, evenly rounded on 

 the periphery; volutions slender, nearly round, the inner or coiled ones 

 forming only a very small part of the entire shell, and so closely invo- 

 luted as to leave only a very small umbilical pit; extended body-portion 



1 Fossil Cephalopoda of Southern India, PL xxxvn. 



