262 THE DEVONIAN OF MISSOURI. 



obseived. Surface marked by concentric striae which bend slightly upwards towards 

 the aperture. At irregular, but wide intervals there are shallow depressions paralleling 

 the striae; these are especially noticeable near the aperture. 



Remarks — The interior of the dorsal side has been observed. The form bears a 

 close resemblance to the large specimen of Hyolithes oxys Clarke, with this difference, 

 that the longitudinal grooves present in that form are lacking here, and the concentric 

 striae bend towards the aperture instead of towards the apex. 



Horizon — Lower beds. 



Figured specimen No. 27510, Walker Museum. 



Suborder Conulariida 



Family Tentaculitidae 



Genus Tentaculites Schloth 



Tentaculites elongatus Hall 



Plate 69, figure 18 



1859. Tentaculites elongatus Hall, Nat. Hist. N. Y. Pal., vol. 3, p. 136, pi. 6, figs. 16-21, 



1861. 

 1908. Tentaculites elongatus Clarke, Mem. N. Y. State Mus., vol. 9, pt. 1, p. 118, pi. 



12, figs. 8, 9. 

 1913. Tentaculites elongatus Ohern, Geol. Surv. Low. Dev., p. 485, pi. 87, figs. 

 8-10. 

 Description — A few fragmentary specimens belonging to this. species occur. The 

 elongate and tapering form, and the strongly marked annulations are unmistakable 

 evidence of their identity with this common Oriskany species. The absence of the 

 fine, closely arranged annular striae which are characteristic of this species, is doubtless 

 due to the condition of preservation. 

 Horizon — Lower beds. 

 Figured specimen No. 27511, Walker Museum. 



ARTHROPODA 



Class CRUSTACEA 



Subclass Trilobita 



Order Opisthoparia 



Family Odontopleuridae 



Genus Acidaspis Murchison 



Acidaspis sp. undet. 



Plate 71, fig. 1. 



Description — This species is represented by a single fragmentary cranidium, ap- 

 parently semi-circular in outline, glabella convex, elongate and narrow, sides straight, 

 separated from lateral lobes by distinct longitudinal furrows. Posterior lateral lobes 

 well defined, small, suboval, anterior pair obsolete or missing entirely. Occipital furrow 

 broad and shallow, but behind the posterior lateral lobes depressed into deep, circular 

 pits. Occipital segment well defined, covered with pustules. Surface of glabella and 

 lateral lobes also marked with pustules which vary considerably in size. 



Cheeks, thorax and pygidium unknown. 



