276 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [April 14, 



main seam of coal in Chesterfield county. It is the same one which 

 was described by Mr. W. C. Redfield, under the name of Catopterus 

 macrurus (Silliman's American Journal of Science, 1841, vol. xli. 

 p. 27). The following are the characters given by him : — 



Catopterus macrurus^ Large-finned Catopterus. This beautiful 

 species is distinguished by its broad and flowing fins, of which the 

 anal is so extended as to be nearly joined by the caudal fin. The 

 latter is finely extended. The length of this species is from four to five 

 inches ; its width from one and one-eighth to one and three-eighths 

 of an inch. The margins of the fins are remarkably fine and beau- 

 tiful. The posterior margin of the scales seems to be curled slightly 

 outward, giving the surface a somewhat roughened appearance. 



The genus Catopterus was instituted by Mr. Redfield for certain 

 species of heterocercal fish from the Connecticut red sandstone, and 

 the species under consideration having, as before stated, a homocercal 

 tail, cannot be comprehended in it. Sir P. Egerton also remarks, 

 that the dorsal fin is more strictly opposite to the anal than in Ca- 

 topterus Redjieldi, which in this respect approaches nearest to the 

 species under consideration ; the tail, according to Agassiz and Sir 

 P. Egerton, bearing the greatest resemblance to that of the genus Pho- 

 lidophorus. The numerous and uniform articulations give to its large 

 anal fin a net-like appearance, which has led Sir Philip to suggest 

 the generic name of Dictyopyge — from Siktvou, net, and Trvyrj, anus. 

 The specific name of Mr. Redfield must of course be retained. 



I procured several specimens of this ichthyolite, the most perfect 

 of which here figured (PI. VIII.) is exactly 6 inches long from the 

 mouth to the extremity of the tail, and 1^ inch broad, but some were 

 a fifth shorter. I do not observe the curled appearance mentioned 

 by Mr. Redfield, in the posterior margin of the scales, which may 

 have arisen perhaps from their being in a disturbed or injured state. 

 The somewhat lengthened shape of the scales of the lateral line, 

 pointed out to me by Mr. Dinkel the artist, causes a marked dividing 

 line between the scales above and below it. In figure e, PI. VIII., the 

 peculiar shape of these scales of the lateral line will be seen, some of 

 them having the opening of the tube outwards, others not, and the 

 projection of the tube in the anterior part of each scale fitting into a 

 notch in the scale immediately preceding. 



fy PL VIII., shows the shape of the scales immediately above and 

 immediately below the lateral line, in which there is a small 

 notch or incision not exhibited in the remoter scales. 



b, PI. VIII., represents the large anal fin, also seen more fully de- 



veloped in fig. b, PL IX. 



c, PL VIII., shows a faint impression of the pectoral fin. 



d, PL VIII., shows part of the ventral fin and an impression of 



the rest. 

 Plate IX. fig. 1 . represents the posterior part of Bictyopyge ma- 

 crura, obtained in the same slab as the specimen figured in 

 PL VIII. ; d is the ventral, and b the anal fin. 



I may also remark, 1st, The opercular and frontal bones of the 



