836 PROFESSOR W. C. M'INTOSH AND MR E. E. PRINCE ON 



paratively small specimens are productive. Northern writers give the end of winter as 

 the spawning period. 



After the stage in which the young of this species and Pleuronectids generally re- 

 semble the larval condition of other fishes, they begin to exhibit an increasing depth of 

 the body, disproportionate to their length. In the earlier stages, when about 4 '5 mm. in 

 length, this flattening and depth of the body are diagnostic. Towards the tail an 

 abrupt narrowing occurs, and the slender embryonic tail proceeds therefrom as a tapering 

 straight process bordered by the embryonic fin, which runs from the head dorsally all 

 round to the anus. The rays are longest at the base of the slender caudal process. 

 Another feature of moment is the ventral projection of the abdomen, for it extends much 

 beyond the line of the body as a prominent swelling. As aids in diagnosing the mutilated 

 young flounders of this stage are the proportionally larger eyes in the young round fishes, 

 and the structure of the tail ; the depression of the snout between the eyes is also a 

 noteworthy feature. The eyes, it need scarcely be mentioned, are quite symmetrical, as 

 in other fishes. 



The most prominent feature in the next stage is the thrusting upward of the terminal 

 caudal " whip" by the development of the hypural elements and the inferior true fin- 

 rays. The ventral margin is also often finely dotted on each side with black pigment. 

 The hypural cartilages so largely increase that they form a deep vertical boundary to 

 the tail, the terminal (notochordal) process being bent upwards, and appearing, when 

 viewed externally, as a slight filament. The depth of the body at the base of the tail 

 has greatly increased. The left eye now shows a tendency to move forward and upward, 

 and a slight twisting of the frontal region is discernible, so that the symmetry of the head 

 is no longer perfect. Small lateral buds indicate the ventral fins. 



The most advanced specimens measured about 13 mm., and when one was placed 

 on its side a small part of the left eye was visible above the margin of the head. 

 Moreover, that eye was slightly anterior to the right eye, and its axis was directed 

 somewhat forward. On the right side four black pigment-spots were situated at the base 

 of the interspinous bones, and the same number, besides specks on the body posteriorly, 

 occurred along the ventral region. On the left side only two were visible along the dorsal 

 line, and a few scattered specks along the ventral, as well as on the posterior part of 

 the body. The general outline of the body strongly suggested that the species was no 

 other than the long rough dab, but the mouth seemed to be similar to the common dab. 

 This latter feature may, however, readily alter afterwards. The dorsal and anal fins are still 

 joined to the caudal by a marginal membrane without rays. This form ranged from 5 mm. 

 to about 13 mm., and was captured in the mid-water net at the end of August. Next 

 year (1887), however, similar specimens were procured towards the end of July, and one 

 reached 14 mm. in length. Their distance from the shore, and the depth of water, 

 besides their structural features, gave grounds for connecting them with the species 

 mentioned. The young of the common flounder at other stages appear to approach it 

 very closely. 



