456 THE ZOOLOGIST. 



narrow ribbon on the edges of the branchial arches, and fit 

 so closely as to make a very efficient filter. The upper pharyn- 

 geal teeth are represented by two soft circular patches of 

 concentric circular corrugations round a central nucleus of 

 papillae. The plan of the lower pharyngeal teeth is occupied by 

 soft papillae. 



EmBIOTOCIDjE. 



A family of viviparous fishes frequenting the North Pacific 

 Ocean. 



Neoditrema ransonettii, a fish from Japan, has sixteen horny 

 gill-rakers on the cerato-hypo of the first branchial arch, the 

 longest of these about two-thirds of the depth of the gill-laminae 

 below it ; there are six similar ones on the first epibranchial. 

 Those on the cerato-hypo portion bend over in the forward 

 direction, and have soft bristle-like projections on them. The 

 other arches have tubercular gill-rakers that fit in from opposite 

 sides and make a close filter. The upper pharyngeal teeth are 

 in two groups, one each side, of strong conical teeth set close 

 together. The lower pharyngeal teeth are in a triangular group, 

 set across the floor of the gullet, of similar teeth, the row nearest 

 the oesophagus being rather larger than the others. The lower 

 pharyngeal bones are united. (See fig. L, 1, which has been 

 enlarged to twice the natural size to show the teeth more clearly). 

 The top of the gullet has been divided, and folded sideways each 

 side, to enable the lower pharyngeal teeth to be more clearly seen. 

 This had to be done also with the illustration of the pharyn- 

 geal teeth of the Labridcs* The similarity in the pharyngeal 

 dentition would point to a similar molluscan and crustacean diet. 



Hysterocarpus traski, a fish from California, has eight horny, 

 moderate-sized gill-rakers on the first cerato-hypobranchial arch, 

 and seven on the epibranchial. The length of the longest is 

 about half the depth of the gill-laminae below it. The inner side 

 of the first, and both sides of the second, third, and fourth arches 

 are set with tubercle gill-rakers that fit in from opposite sides and 

 form a close filter. The upper pharyngeal teeth show as a 

 roughly circular group, on each side, of conical teeth with some 

 in their middle of a rounded granular shape, possibly due to 

 their being more ground down ; they are the largest in the 

 * See ' Zoologist,' December, 1911, p. 454. 



