28 bulletin: museum of comparative zoology. 



little of it, and the anterior part of the ethmoid, as seen by the final 

 position of the anterior ends of the pterygo-palatines, having turned 

 not more than 45 degrees. 



In the turbot, according to Traquair ('65, p. 276), the nasal region is 

 nearly normal in position, the sagittal plane of the anterior part of the 

 head nearly coinciding with that of the body. 



f. Comparison of Bothus with Pseudopleuronectes americanus. 



The nearest representative in American waters of the sinistral turbot 

 is Bothus, the sand-dab, and I shall now compare briefly its turning 

 with that of P. americanus. The sand-dab is much deeper than the 

 flounder, but being thinner, though of the same length, it weighs about 

 the same as that fish. Its translucency has gained for it the name of 

 window-pane. 



Traquair's statement that the turbot is less unsymmetrical than the 

 plaice holds as truly here, the sand-dab being less distorted than the 

 winter flounder. The mouth is straight and the length of the jaw on 

 the ocular and eyeless sides is more nearly equal. The mouth is much 

 larger and the gape greater than that of the winter flounder. The nasal 

 pits are very nearly symmetrical, that of the right side being, however, 

 a little the higher (Plate 3, Fig. 13). The transposed eye is not at all 

 posterior to its mate, as is the case in P. americanus. The dorsal fin in 

 this species reaches forwai-d entirely past the riglit eye (Plate 3, Figs. 13, 

 16, crt. pin. (1.). After the passage of the eye, the bases of the fin rays 

 arise nearly over the right wing of the ethmoid. 



The ethmoid is relatively a much more slender cartilage in Bothus 

 than in P. americanus. The cross section of its anterior end (Plate 3, 

 Fig. 13) has the shape of an inverted letter T, and its dorsal margin is 

 turned not more than 20 degrees to the left from the sagittal plane. In 

 the posterior region (Fig. 16) the ethmoid is turned about 45 degrees. 

 The relation of the cartilage marked trb. su'orb. s. to the ethmoid mass 

 in Figure 16 indicates the angle, though the median bar itself is farther 

 forward. The wings of the ethmoid fuse to the median bar in a peculiar 

 way. The right wing (ec'etk. dx. Fig. 13) points toward the rays of the 

 dorsal fin which lie next it. It does not connect with the basal part of 

 the ethmoid directly, but merely with the median upright part. The 

 left wing has a process running anteriorly into the region of the lip 

 at the level of the basal part of the ethmoid, with which this wing is 

 fused. It then passes around the olfactory nerve of its own side, be- 



