14 Fishery Board for Scotland. 



have already the appearance characteristic of the fully developed post-larval 

 form. 



The largest post-larva described by Stiasny measured 55 mm., but he thinks 

 that, when about 80 mm. long, they seek the ground, the natural habitat of the 

 adult. 



Small Bottom Stage of 64 mm. 



{Fig. 9). 



Unfortunately, there is a considerable gap in the series between the largest 

 post-larval form and the smallest bottom stage caught in Scottish waters. There 

 is no difficulty, however, in recognising the specimen of 64 mm. in length as a 

 young Angler, on account of its close approach to the typical adult form. 

 Although many of the changes leading up to this form have been radical, they 

 have not yet been completed, and it is therefore of interest to compare this stage 

 with the preceding one, as well as with the larger forms. 



A small bottom form of 124 mm. (preserved in formalin) has already been 

 described by Fulton (1902). It was caught in the month of July in the Dornoch 

 Firth in a depth of 8 to 11 fathoms. As it has many characters in common with the 

 smaller specimen, Fulton's description has been incorporated in the present one. 

 The relation of the 124- mm. specimen to a series of small bottom forms, which 

 have been examined, is considered later. 



The transference from a pelagic to a bottom habit has involved many changes 

 both in form and in the relation of the paired and unpaired fins. 



The small specimen of 64 mm. in length is still soft and gelatinous, with an 

 abundance of mucoid tissue in the head region. 



The change in form has been brought about mainly by the enormous lateral 

 expansion of the bones of the head behind the eyes. The greatest breadth of the 

 head behind the eyes is now almost one-and-a-half times the distance from the tip 

 of the upper jaw to the occiput, and almost twice the greatest depth of the head. 

 The actual measurements are : breadth behind the eyes, 23 mm. ; distance fiom 

 tip of upper jaw to occipital region, 16 mm. ; depth at occipital region, 13 mm. 

 The body narrows suddenly behind the head ; its breadth, just behind the gill- 

 openings, is 8 mm. The body and tail form an elongated truncated cone slightly 

 flattened on the ventral surface. The distance from the occiput to the end of the 

 tail peduncle is 32 mm., and the breadth at the tail peduncle, 4 mm. The breadth 

 of the body at the head is masked by the disposition and size of the pectoral fins. 

 The angles of the large mouth are in a line with the anterior margins of the eyes ; 

 the gape with the mouth closed is 19 mm. The eyes are 5 mm. in diameter, and 

 the concave interorbital space is only slightly greater than the diameter of the 

 eyes. The eyes have, therefore, lost their original lateral position on the head. 



The pectoral fins are large, the fan-like portion being equal to the length of the 

 head. They are pigmented at the tips, but there are no filamentous prolongations 

 of the rays. The membrane between the rays is still delicate and the fin is capable 

 of considerable expansion. The lateral growth of the bones of the head behind the 

 eyes has been accompanied by the rotation of the pectoral fins through a right angle, 

 so that the surfaces of the fins, when expanded, are now in a horizontal plane, and, 

 therefore, more adapted to a bottom habitat. The lateral expansion of the head 

 and the adhesion of the edges of the branchiostegal membranes across the isthmus 

 have made the gill-openings appear below the axils of the pectoral fins. The pelvic 

 fins are inserted on the ventral surface very far forward. They are also pigmented 

 at the tips, and are still membranous and capable of expansion. They are much 

 reduced in size, however, but the tips of the rays extend back almost to the anus, 

 which opens immediately in front of the anal fin. 



The first dorsal fin has altered considerably, the six rays being now well developed. 

 The first two rays are very far forward, and arise close to the tip of the snout. The 

 second ray is the larger, and, when stretched along the head, reaches to the base 

 of the third ray. The first ray is only about half the length of the second. It is 

 very delicate and destitute of lateral appendages or fringes, but bears on the tip 

 a small membranous horizontal appendage about 4 mm. long, attached by the middle. 

 This membranous appendage is usually curled on itself in preserved specimens. 



