.524 LONSDALE ON EOCENE CORALS FROM N. AMERICA. 



in width ; the branches also exhibited nearly their full dimensions 

 from the very points of divergence, springing upwards after a 

 short curve almost vertically. The portion occupied by the tubu- 

 lar openings formed but a small part of the circumference of the 

 branch ; and when a fragment was placed horizontally and side- 

 ways with the rows of apertures upwards, the latter bore some 

 resemblance to a series of teeth in a maxillary bone. The mouths 

 were generally limited to three in each row, the outermost being 

 the smallest. The great range of the tubuli explained apparently 

 the considerable dimensions of the reverse portion, the interior of 

 the branches consisting almost wholly of tubes, of one character, 

 but decreasing in size from front to back. The uniform semi-oval 

 outline of this portion would apparently indicate that the branches 

 were free, or not affected during growth by pressure : nevertheless, 

 a triangular shape does not, it is presumed, necessarily imply 

 an attached reversed surface, M. Milne Edwards's figure of I. 

 radians having a decided broad pedicle, though the branches have 

 " la forme de prismes a trois plans" (Recherch. sur les Polyp., 

 Mem. sur les Crisies, &c. p. 25. pi. 12. f. 4.). M. Milne Edwards 

 was, however, fully justified in making the inference that I. tri- 

 quetral on account of its slightly concave reverse surface, was 

 probably attached to the stem of a marine plant, there being in the 

 fine collection of oolitic polyparia in the cabinet of Mr. Walton, of 

 Bath (England), a specimen believed to be referable to that spe- 

 cies, attached dorsally to a Terebratula obtained from the Brad- 

 ford clay. It is scarcely necessary to remark, that species of 

 other genera of Tubuliporidae are affixed indifferently to fuci, 

 testacea, or pebbles. 



The whole of the reverse surface exhibited white longitudinal 

 lines, with interspaces much less in width than the diameter of the 

 tubuli. Their true nature was not ascertained, but it was believed 

 that they were not the walls of capillary tubes, similar to those 

 which constitute the reverse side of old specimens of Hornera, as 

 they occasionally united, and the interspaces were crossed by irre- 

 gular filaments. No exterior thickening or change dependent 

 upon age was noticed ; and a fixed dorsal surface seen in some 

 species, would prevent, it is presumed, all marked alterations on 

 that side, as it is difficult to conceive that polypes generically iden- 

 tical could possess in certain species a complicated series of vessels 

 requisite for developing a considerable additional surface, and 

 want it in others. 



Locality. — Wantoot, South Carolina. 



13. Idmonea commiscens. (sp. n.) 



Branches forked, triangular; rows of tubular opening extended nearly to the 

 dorsal surface ; no medial ridge or furrow, but an intermingling of mouths ; 

 range of tubuli limited ; reverse or dorsal surface irregular in outline. 



In the triangular form of the branches this fossil resembled the 



