﻿34 H. M. Seely — Genus Strep hochetus. 



rium Riclvmondense Miller. This form was originally referred 

 to Stromatocerium with hesitation, the choice seeming to lie be- 

 tween that and Stromalopora. After making many sections it 

 becomes evident that it most nearly approaches the genus 

 Strephochetus. Mr. Miller has authorized the specific descrip- 

 tion above, and it is to be known as Strephochetus Rich- 

 mondensis. 



This species has several peculiarities of structure. Not un- 

 frequently it occurs as an incrusting body, having for its core 

 a bit of coral, or a fragment of the shell of a brachiopod. It 

 sometimes resembles the structure of S. Brainerdi in the great 

 enlargement of its canals. In this species, however, the tubes 

 present great uniformity of direction though not of size. They 

 run along nearly parallel with each other for a little distance, 

 and then are cut short by a laminar covering which may be the 

 basis for a similar set of slightly radiating tubes. This may 

 be repeated as described in the specific characterization of the 

 fossil, ten or fifteen times. 



Sections cut in either direction, horizontal or perpendicular, 

 suggest the genus Solenopora, while those of S. Brainerdi, in 

 like manner that of Chcetetes. The discovery of septa or tabulae, 

 in either of these tubular forms, would lead one at once to place 

 it among the millepore corals. The character of these forms 

 deepens the impression that the line between corals and sponges 

 becomes in some places very narrow and indistinct. 



The horizon of these different species is as follows : S. ocel- 

 latus, near the middle of the Chazy ; S. Brainerdi, in the upper 

 Dove, higher in the Chazy ; S. atratus, in the Black River ; 

 S. Richmondensis, in the Hudson River. 



The appearance of the members of the genus may be repre- 

 sented by the smaller fruits, currants, gooseberries and cherries, 

 distributed through a paste of oolitic, fragmental or subcrystal- 

 line material. These in most cases have apparently been sub- 

 jected to pressure and left in a crushed or torn condition. In 

 weathered specimens they show a concentric structure, more or 

 less regular, which is helpful in distinguishing the genus. 



There are intimations that the genus exists in rocks higher 

 than those mentioned, and it is quite probable that forms which 

 have hitherto been regarded as concretionary or as pebbles, 

 will on examination be found to belong here. The structure, 

 which for lack of better term, we have called Strephochetal will 

 be decisive on this point. 



It would be highly satisfactory if it should be found, as is 

 quite probable, that the strephochetal structure always indicates 

 the presence of a sponge. In that case we might by it, .hope to 

 settle the question of relationship, now uncertain, of several 

 important genera. 



Middlebury College. 



