NATURAL SCIENCES OF PHILADELPHIA. 117 







elevated ridges, radiating on the surface of the opercula, from the margin of 

 the central opening to the outer circumference. In a species of Fistulipora, 

 subsequently to be described, I found opercules of exactly the same struc- 

 ture. Also some species of Callopora, with a spinulose surface, are made known 

 by Hall, which exhibit no essential difference from the spinulose species of 

 Chaetetes. 



The floriform orifices of Callopora floi-ida, Hall, and laminata, Hall, have 

 been occasionally mentioned before. The same stellate character of the ori- 

 fices is developed in a species from the carboniferous limestone of La Grange, 

 Missouri, (Keokuk Limestone.) 



Callopora missouriensis nov. spec. 



From an incrusting basal expansion branching nodose stems grow up. 

 Diameter of stems four or five millim., orifices one- eighth of a millim. wide, 

 distant from two to four of their own diameters. Form of the orifices some- 

 times only slightly sinuose, but in some finely preserved specimens, having 

 the form of a five-rayed star, with a spinula on each of the inward project- 

 ing angles. 



The intermediate spaces are filled with open angular cells, much smaller 

 than the tubules. In vertical sections the tubes do not exhibit any dia- 

 phragms ; the intertubular cell mass forms very regular vertical rows, having 

 the appearance of septate tubules. 



The genus Trematopora Hall, naturally succeeds Callopora. The principal 

 differences from the latter genus are the elevated rims of its tube orifices, and 

 the generally closed interstitial cells, which are less similar to tubules than 

 in Chaetetes, and show decidedly their vesiculous nature. The tube dia- 

 phragms are not often developed, but there is no difficulty to find specimens 

 in which their existence can be demonstrated. 



Not all species united by Hall in the genus Trematopora properly belong 

 there ; for instance, Trematopora sparsa, striata, and others. On the other 

 side, I think several species ought to be united with it, which are placed in 

 other genera; as Ceramopora foliacea, Diamesopora dichotoma, etc. 



McCoy's species of Fistulipora seems to have exactly the same structure with 

 Trematopora, but McCoy had much less correct ideas of the affinities of his 

 genus than Hall had; the latter expressly states the similarity of Callopora 

 and Trematopora with the Bryozoa, and was only prevented from giving them 

 their proper place by the existing prejudice, that the tubules of Bryozoa 

 never have any diaphragms. 



1 take Trematopora and Fistulipora as being identical, and will use the 

 name Fistulipora in a more extended sense, applying it to all the species 

 which agree with it in anatomical structure and general surface characters, 

 without to inquire specially at this place, how far a division into some sub- 

 genera, would be practicable. 



Fistulipora is represented by a considerable number of species, during the 

 whole paleozoic era. A striking feature of nearly all its species are super- 

 ficial macule, analogous to those of Chaetetes ; they are of exclusively cellu- 

 lose structure, and have frequently a subregular stellate form. 



A fair representation of these macula^ is given (Arch, du Mus. Tom. v. Tab. 

 20, f. 5,) in the figure of Chaetetes Torubine, which itself is, to all appearances, 

 a Fistulipora. 



The projecting tube margins of Fistulipora are in most of its species 

 oblique to the surface, although the tubes themselves have generally a rec- 

 tangular position to it, excepting the smaller ramose forms, and the earlier 

 stadia of growth in laminar expansions, where the tubules are prostrate in 

 the beginning, but soon elevate themselves under an abrupt angle and be- 

 come rectangular. 



The tube orifices are generally circular, or oval, but sometimes sinuate, or 

 even stellate, like those described in Chaetetes and Callopora. Also opercu- 



1866.] 



