400 



University of California. 



[Vol. 3. 



Some similarity also exists between this spine and the fragment 

 from the Sub- Carboniferous which St. John and Worthen* have 

 described as Glymmatacanthus , but with such evidence as is at 

 hand one would not be justified in establishing any certain 

 affinities between the two. We know nothing of the character 

 of the posterior face of Glymmatacanthus, which, moreover, 

 shows no close agreement in the sculpturing or arrangement of 

 its tubercles and possesses no anterior keel. 



The Paris spine can be included in the genus Gosmacanthus 

 Agassiz as defined by Woodward."!" Its general form, the pres- 

 ence of tuberculation on the lateral faces, and the truncation of 

 the posterior face with low longitudinal keel, are characters 

 which show its relationship to that genus. Of the species which 

 have been included in Gosmacanthus, the Paris specimen shows 

 closest affinity with two which St. John and Worthen have 

 described from the Sub-Carboniferous of Illinois and Missouri, 

 and of these, especially with Gosmacanthus ( Geisacantlms) 

 stdlatus. This spine shows clearly the prominent anterior 

 enamel keel, a character which was apparently absent in the type 

 species, G. malcolmsoni Agassiz from the old Bed Sandstone, as 

 well as in C. marginalis Davis and G. c'arbonarius McCoy, from 

 .the Irish Carboniferous. It may well be questioned whether this 

 character is not of generic rank and if so the name Geisacanthus 

 must be retained for the keeled forms. 



The Paris spine is easily separated from the Illinois species 

 by its much greater size, more numerous tubercles and different 

 tubercular pattern, as well as by the difference in the form and 

 sculpturing of the tubercles. For the present we retain it as an 

 Ichthyodorulite, until further information such as its association 

 with teeth, scales, etc. will permit us to identify it with some other 

 form or certainly fix its generic relationship. 



At the present time, this is, so far as the author is aware, 

 the only Ichthyodorulite recorded from the American Triassic. 



•St. John O. and Worthen A. H. Descriptions of Fossil Fishes. Palaeontology 

 of Illinois. Geol. Surv. of 111. (A. H. Worthen, Director) 1875. Vol. VI, Part II, 

 pp. 446-447; also pp. 440-442. 



t Woodward, A. S. Catalogue of the Fossil Fishes in the British Museum. 

 Part II, 1801, p. 111. 



