Holt and Calderwood — Report on the Rarer Fishes. 439 



end of the 2nd anal, 8 cm., since the last-named fin does not extend quite so far 

 back as the dorsal. ° 



Fins. (D. I. 8; D. ii. 44; A. i. 17 (+ 3); A. ii. 20; P. 19; Pelv. 6, Caud. 

 38, ca.). — The pectorals do not reach the anus; the pel vies, of which the two outer 

 rays are elongated, extend a little beyond the level of the commencement of the 

 first dorsal. The anterior ray of the first dorsal is elongate, and terminates in a 

 filament. It has a total length of 8'5 cm., but has evidently been at some time 

 broken off at about half its present length, and the distal portion appears to be a 

 new growth, and therefore probably shorter than normal. The second ray is a 

 stout arthroneme, 7*8 cm. long ; the succeeding rays are shorter, the last being 

 minute, so that the outline of the fin, apart from the first ray, is roughly triangu- 

 lar. There is hardly an interspace between the two dorsal fins, their membrane 

 being continuous. There is a distinct indentation of the outline of the second 

 dorsal, due to inequality in the length of its rays. Thus the anterior rays are 

 5-3 cm. in height, but at a point somewhat behind the middle (of the fin) the height 

 of the rays decreases to 4-5 cm., increasing again to 5'3 at the thirty-first ray. 

 The rays posterior to this decrease very rapidly, so that the end of the fin is 

 oblique in outline. The incurvature of the dorsal margin is much better marked 

 in this specimen than is shown in fig. 3, PI. xxxix., which is a sketch of a younger 

 example, in which the condition of the fin-rays leaves some doubt as to the natural 

 outline. 



The first anal reaches its full height at about the fourth ray, and decreases 

 towards its posterior extremity in the usual fashion. The seventeenth or last ray 

 of the fin proper is very short but stout, and is separated from the short and very 

 stout ray which is the first of the second anal fin by an interspace of 2*7 cm. The 

 fin membrane, however, is continuous, though much reduced, and from it emerge 

 the tips of three minute and very slender rays. Since the ray, which we have 

 alluded to as the first of the second anal, has all the characters of the anterior ray 

 of a fin, it seems that these three minute interstitial rays must belong to the first 

 anal, if specially to either. As a matter of fact, however, they evidently belong 

 to a primitively continuous fin, and therefore not specially to either of the present 

 (otherwise) separate fins. The reduction of the rays in the central region of the 

 second dorsal is evidently a step in the direction of a sub- division of that fin ; and 

 thus in the genus Mora we have an interesting illustration of a stage in the 

 evolution of separate fins from the continuous primordial fin or fin-membrane. 



The diagrams on pp. 440 and 441 are designed to demonstrate this more forcibly. 

 The figures are intended to show the fins of the adult co-existing with the 

 primordial tin-membrane of the larva. 



Figm-e A represents the lowest term in the Gadoid series in which a distinct 

 caudal fin exists, exemplified by the genus Brosmius. That this condition is derived 



