No. 1.] WHITEAVES DEVONIAN FISHES. 29 



DiPLACANTHUS. 



Two specimens, one shewing scales and longitudinally grooved 

 fin spines and the other a large portion of the body, of a small, 

 smooth-scaled Diplacanthus, very like the D. striatus of Agassiz 

 and possibly identical with that species. 



Phaneropleuron curtum, Sp. Nov. 



General outline, inclusive of the fins, varying in different spe- 

 cimens from subovate to fusiform- : length also varying from a 

 little more than twice to rather more than three times the height. 

 Head small, between one-fourth and one-fifth the entire length, 

 and apparently obtuse in front. Cranial plates minutely pitted or 

 irregularly corrugated. Scales thin, cycloid, imbricating, sculp- 

 tured on their exposed surfaces with exceedingly fine radiating 

 lines, which are visible only under a lens. Dorsal fin single, very 

 long and large, commencing at a point considerably in advance 

 of the middle, at first not much elevated above the dorsal margin, 

 but increasing rapidly in height towards the tail, with whose 

 upper lobe it ultimately becomes confluent. Maximum height 

 of the dorsal nearly equal to the length of the head. Caudal fin 

 heterocercal : anal and caudal fins both extending as far out- 

 wards from the body as the posterior end of the dorsal does, and 

 separated at their bases by a very narrow interval. Anal fin nar- 

 row and elongated, ventrals also long and narrow, and separated 

 from the anal by a space considerably wider than that which 

 intervenes between the anal and caudal. Pectorals unknown. 

 Ribs very slender and well ossified : interspinous bones con- 

 tracted in the middle and gradually expanding at each end. 



Of this species four crushed and distorted but otherwise nearly 

 perfect specimens were collected, which want only the ventral 

 and pectoral fins. Many fragments of this fish also were ob- 

 tained, one of which shews the shape and position of one of the 

 ventrals. The variation in the outline of different individuals 

 and in the proportions which their length bears to their height, 

 is evidently largely due to the distortion to which they have been 

 subiected. The smallest specimens are the least distorted, and 

 in these the length is much greater in proportion than it is in 

 the larger ones. Thus, the smallest individual collected by Mr. 

 Foord is about thirty-four lines long and ten lines high, while the 

 largest is a little more than six inches long and three inches and 

 a quarter high. 



