254 Prof. M'Intosh's Notes from the 



At 6'5 millim. the larval tail is still present. The rows of 

 closely arranged black specks go down to tbe ventral edge, 

 but the median ventral region is free. Two marked pigment- 

 lines exist ventrally on the lower jaw beneath the eye and at 

 the opercular region. 



At 10 millim. tbe lateral rows of chromatophores are still 

 more definitely arranged, forming about four complete longi- 

 tudinal rows on each side, besides minor specks, and the axis 

 of the mandible is more or less horizontal instead of being 

 upturned. The larval tail has almost disappeared, the only 

 trace being the slender tip of the notochord, which slants 

 upward to the dorsal edge of the fin, a true fin-ray occurring 

 immediately beneath ; but the marginal fin with embryonic 

 rays connects it with the doi'sal, in which true rays are 

 developing. Rudimentary true rays also mark the first part 

 of the anal fin. The sucker appears to be nearly complete, 

 but is proportionally much smaller than in the adult, probably 

 because the habits are less sedentary. These characters 

 remain at 10'5 millim., except that there are now five short 

 true rays on the proximal side of the slender tip of the noto- 

 chord in the tail, and it is evidently rapidly disappearing. 

 Such stages are met with in September and October. 



In December the young bimaculated suckers reach 15"5 

 millim., and then are met with in the stomachs of food-fishes. 

 Long before this stage all trace of the caudal notochord has 

 disappeared. The tip of the snout is much more flattened and 

 the eyes proportionally larger and more prominent. The 

 sucker has also considerably increased in size. 



In February the young are from 21 to 22 millim. in length 

 and more or less resemble the adult, though the tail is large 

 and shows two or three additional rays, that is about fifteen 

 instead of twelve. The vent is now nearly median, whereas 

 in tliose of 10 millim. it was situated at the commencement 

 of the posterior third. It also presents symmetrical longi- 

 tudinal rugse which end in short papilloe around the aperture. 

 The rays in both dorsal and anal fins are six (Day gives 

 D. 0-7, A. 4-6). The anterior division of the sucker is 

 minutely papillose, so that its free margin seems to be 

 serrated, and the surface of the median area and two lateral 

 arms is covered for some distance with the same papillae. 

 The surface of the larger posterior division is also minutely 

 papillose, but the margin has none of the larger papillai seen 

 in the anterior division. A thin serrate or crenatc membrane 

 forms a broad border to the posterior half of its margin, and 

 at this stage it is, in some at any rate, quite free from the 

 margin of the sucker. A broad diaphanous and striated flap 



