152 Professor C. E. Beecher — Structure of TriloUtes. 



is arcuate ia form, with an extreme length of about 24 cm., and 

 comprising twenty fused teeth, only four of 

 which, however, are perfectly pi'eserved. A 

 transverse section of the specimen taken verti- 

 cally from the apex of the largest tooth, where 

 the height is about 8 cm., is shown in Fig. 3. 

 All the teeth have suffered greatly from the 

 effects of weathering, which has removed most 

 of the enamel, and from post-mortem abrasion. 

 In general form they resemble those of Belico- 

 prion bessonowi, but are less angularly bent, in 

 which respect they differ also from C. davisii ; 

 in addition, their apices are more obtuse and 

 more coarsely serrated. Both of these species 

 of Campyloprion differ from the Russian form in 

 their lesser degree of curvature, and it is ex- 

 tremely improbable that either of them was 

 coiled into a complete spiral. Neither do they 

 exhibit the double lateral grooves which traverse 

 the spirals oi Helicoprion. It is possible that the 

 indistinct patches of enamel observed along the 

 base of the present specimen may represent an 

 adjacent series of small teeth, such as occur in 

 juxtaposition to the symphysial series of Cam- 

 podiis variabilis. A more detailed account of the 

 dentition of the latter form will be given in 

 a forthcoming number of the Bulletin of the Vertical section of Pig. 2. 

 Museum of Comparative Zoology. Campyloprion anneetans. 



EXPLANATION OF FIGUEES. 



Pl. VIII, Fig. 1. — Campodus variabilis (Newb. & W.). Coal-measui-es : Cedar 

 Creek, Nebraska. Symphysial series of teeth belonging (presumably) 

 to the lower jaw, viewed from the right-hand side. Original preserved 

 in the Museum of Nebraska State University at Lincoln. Eeduced to 

 about one-half nat. size. 



Pl. VIII, Fig. 2. — Gamj^yloprion anneetans, gen. et sp. uov. Carboniferous or 

 Permian : locality unknown. Left lateral aspect of a portion of the 

 anterior dentition, showing portions of 20 coalesced teeth, supported at 

 their bases by a band of calcified cartilage. Eeduced. 



Fig. 3 (in text).- — Camptjloprion annecta?is. Vertical cross-section of specimen shown 

 in Fig. 2, passing through apex of largest tooth in the series. Eeduced 

 to about one-third nat. size. 



III. — The Ventkal Integument of Tkilobites.^ 



By Professor Charles E. Beechek, Ph.D., For. Corr. Geol. Soc Lond., 



Yale University, New Haven, Conn., U.S.A. 



(PLATES IX-XI.) 



IN previous papers by the writer on the structure and appendages 

 of Triarthr us, '^ no attempt has been made to describe or illustrate 

 the character of the ventral integument, especially in the sternal or 



1 Eeprinted by permission from the Amer. Journ. Sci. [4], vol. xiii (1902), 

 pp. 165-174. 



2 C. E. Beecher, " On the Thoracic Legs of Trilobites " : Amer. Journ. Sci. [3], 



