188 THE SUCKER FAMILY. 



to the commencement of the anal fin. The third line has the 

 best marked papillae. 



At 18 mm. some are variegated with fine touches of silvery- 

 white, one or more on each side of the abdomen, and two at 

 the base of the pectoral, the latter inferiorly being reddish 

 brown, as is also the tip of the dorsal. The eyes are silvery 

 with reddish brown round the margin of the pupil. 



It is interesting that in the American examples Professor 

 A. Agassiz found no trace of these papillae in fishes 20 mm. 

 long, yet the anterior part of the body, he observes, had 

 assumed the somewhat angular outline characteristic of the 

 adult, though the body, as a whole, was longer. Indeed, he 

 found the spiny tubercles (of which the foregoing papillae are 

 the precursors) developed only to a slight extent in young forms 

 measuring 34 mm. The British examples are thus more 

 precocious. Professor Agassiz also describes ' a last row of 

 somewhat smaller tubercles along the median line of the 

 abdomen behind the ventrals.' In all probability 'median' 

 should be ' lateral,' unless the American form specifically 

 differs. 



As the fish increases in length, the second and third rows 

 extend posteriorly, and by-and-by become hispid with minute 

 spines ; the third, especially, presenting large crescentic 

 eminences bristling with prominent spines, which, while oc- 

 curring over the tubercle generally, also form a pectinate ridge 

 distally. 



In June the young lump-suckers range from less than 

 10 mm. to 23 mm., the smaller forms being more frequent at 

 the beginning, the larger towards the end of the month. In 

 those of 23 mm. the spiny tubercles are all better marked than 

 at 19 or 20 mm. Thus, the second and third rows (lateral) 

 extend to a line passing through the middle of the second 

 dorsal and the anal. In full development each process in the 

 row forms a multispinous tubercle. A row of small spinous 

 tubercles also occurs at the lower border of the opercular 

 region, one extending to the branchiostegal area. At this 

 stage (23 mm.) the second dorsal has 11, the breast-fins 21, the 

 anal 10, and the caudal 11 rays — these numbers agreeing for 



