﻿TRHMATASPID.E. 



201 



Family TREMATASPID^E. 



Shield rounded or tapering in front, abruptly truncated behind ; 

 interorbital piece not fixed ; external surface, covered with punctate 

 ganoinc, the punctations often arranged in reticulating lines; super- 

 ficial tuberculations almost or entirely absent. 



Genus TREMATASPIS, Schmidt. 



[Verhandl. russ.-kais. mineral. Ges. St. Petersburg, [2] vol. i. 

 I860, p. 233.] 



Syn. (?) Stiymolepis, C. H. Pander, Foss. Fische Silur. Syst. 1856, p. 53. 

 Odontotodus, C. H. Pander, ibid. p. 75 (inappropriate). 



Shield simple, the postero-lateral angles not produced into cornua ; 

 a continuous ventral plate opposed to its posterior two-thirds. A 

 circular depression immediately in advance of the orbital opening, 

 with an antero-posteriorly elongated cleft in the centre; an oval 

 fossa or cleft behind the orbital opening. 



In the ordinary state of preservation of the shield it is difficult to 

 distinguish broken eminences and depressions from vacuities ; and 

 it is quite possible that the post-orbital and lateral openings 



Fig. 32. 



Fig. 31. Tremataspis schrenki (Pander). — Outline of shield, dorsal aspect, 



after F. Schmidt. 

 Fig. 32. Tremataspis schrenki (Pander)- — Outline of anterior portion of shield, 



ventral aspect, after F. Schmidt, 



described by Schmidt are due to features of this kind accidentally 

 removed. The appearances are distinct in the original specimens, 

 and, whether they be due to vacuities, eminences, or depressions, 

 they are at present not readily interpreted. 



