ON DORYPTEKUS HOFFMANNI. 265 



ridge is quite distinct, and the continuity of the dark enamel- 

 like surface -matter with that covering the lateral plates is very- 

 obvious. 



Considerably more of the dorsal fin (a) is present than in any 

 of the other specimens. One inch and three-quarters of it, in a 

 good state of preservation, inclines backwards ; and in front, 

 arranged in exact order, are twelve or thirteen short plates, the 

 fin-fulcra (a"); but these so imperceptibly graduate into the 

 regular rays that it is difficult to determine the exact number ; 

 they are strong, pointed, and have the root distinctly rounded. 

 The broken extremity of the fin is a little less than two-tenths 

 of an inch wide ; and from this we infer that more than one- 

 half of this fin is wanting. In this specimen it would probably 

 be a little short of four inches long. There are twenty-four or 

 twenty-five rays at the base of this elongated portion, including 

 the short anterior plates or fulcra ; and one inch and a half up 

 only seven or eight can be counted. Very little is to be seen of 

 the narrow posterior portion of the fin, there being only a slight 

 trace of a few rays. 



The pectoral fins (c) are in a pretty perfect condition, occu- 

 pying their natural position immediately behind the posterior 

 angle of the gill-covers, one partially overlying the other. At 

 the root of one of them there are two flat curved bones, which 

 may perhaps be respectively the scapula and coracoid. Arising 

 from these are the brachials (c'), to the number of fourteen or 

 fifteen ; they are about one-eighth of an inch long, and are deli- 

 cate and flat, thicker than the fin-rays, with the extremities ob- 

 tuse ; and there are two simple rays, composed of many joints, 

 to each brachial. 



The remains of both the ventral fins (d) are seen in front of 

 the ventral plates, the edge of the belly being turned a little up- 

 wards. Two elongated bones, nearly a quarter of an inch long, 

 lie in contact with them, and have their anterior ends a little 

 enlarged and nodulous. These are probably the pelvic bones, 

 to which the fins are attached, the thickened extremities having 

 all the appearance of articular surfaces. The mere casts of 

 these bones are observed in connexion with the specimen ; but 



