THE SUCKER FAMILY. 1<S5 



the tail and the pectorals. The heavy anterior end of the body 

 is thus favourable for progression. The dorsum is pale brownish. 

 The pectorals are pressed closely to the sides when at rest, so 

 that the outline of the fish is that of a short dagger. In Prof. 

 Agassiz's 1 youngest stage the caudal was already partly separated 

 from the dorsal and ventral embryonic fin, and yet the presence 

 of yolk is not mentioned, though the length is only 4 mm. 

 The foregoing, therefore, while larger, was less developed ; as, 

 indeed, his figure shows. He fancifully likens the outline to 

 that of the armoured fishes of the Old Red Sandstone, e.g. 

 Coccosteus. By the 12th day the fish has increased considerably 

 in bulk, and measures 675 mm. ; and in spirit, besides the 

 disappearance of the yolk and the increase of pigment, the 

 dorsal has now been transformed into two fins (Plate VII, 

 fig. 10), a short crescentic first dorsal, over the vent, having G 

 true rays, and a second dorsal, with 11 true rays, joined by a 

 portion of the larval fin (which shows no embryonic rays) to 

 the caudal, the upper region of which (the larval tail) has only 

 embryonic rays to the notch", 10 true rays occurring beneath. 

 The anal fin has 10 rays, and is joined to the caudal by a strip 

 of larval fin without rays. In the figure of Professor Alex. 

 Agassiz at this stage (e.g. fig. 3, Plate IV), the second dorsal 

 shows 13 rays, the anal 15, and there is no connection between 

 these fins and the caudal. He likens it to the young of 

 Batrachus. 



Professor A. Agassiz gives some excellent remarks concerning 

 the coloration of these young forms. ' In the youngest stages ' 

 (with true rays developing in the tail, or about the 12th or 13th 

 day in Britain), ' the head, in a line drawn nearly vertically 

 below the base of the anterior dorsal, is of a light chocolate 

 brown, with a darker brown band extending from the nostrils 

 above the eye to the base of the anterior dorsal. A light blue 

 band extends from the rear of the eye to the top of the oper- 

 culum and in front of the eye to the nostrils. A blue spot of 

 similar tint is found at the posterior base of the dorsal and at 



1 Proceed. Amer. Ac. Arts and Sc., vol. xvii., July 1887, p. 286. 



2 The notch is absent in Professor Agassiz's figure (PI. IV, tig. 1). 



