The 7<latural History of the Frilled Shar}{ 



287 



one of Doderlein's specimens previously referred 

 to. Rose's observations in general agree with 

 Carman's, but his figures are drawn to larger 

 scale and are much clearer. We reproduce 

 here his figures 1, 2, 3, and 4 as our Text-fig- 

 ures 14, 15, 16, and 17 respectively. Text-figure 

 14 shows a placoid scale from. the flank. This 

 (viewed from above) shows the prominent spine 

 and the ridges extending from the base to the 

 apex of the spine. These ridges are four in 

 number, three visible and one concealed by the 

 spine itself. Text-figure 15 shows a dermal 

 denticle taken from the side of the tail. In this, 

 the ridge on the right of the figure is the ridge 

 which is concealed when viewed from above 

 as in Text-figure 14- In Text-figure 16, the 

 scale from the caudal region is viewed from 

 beneath and shows the pulp-cavity. Text-figure 

 17 shows some large dermal denticles from the 

 region of the dorsal fin. Viewed from above in 

 their natural position and orientation, they give 

 an excellent idea of the appearance of the sha- 

 green in a region where this is well developed. 

 Certain well-developed and highly special- 

 i2;ed scales form the "armature" (as Carman designates it) found on the anterior edges of 

 the dorsal fin and of the dorsal lobe of the caudal fin. These are portrayed by Carman 

 (1885.2) in his PI. VI, fig. 11 — our Text-figure 23. For a discussion of these scales see 

 our description of the caudal fin (page 294). 



Text-figure 17 



Dermal denticles (x30) from the dorsal fin of a 



340-mm. uterine embryo of Chlamydosehchus 



shown in^their natural arrangement. 



After Rose, 1898. 



SENSORY CANAL SYSTEM AND ASSOCIATED ORGANS 



The sensory canal or lateral line system consists of a sensory canal running along 

 each side of the body and branching over the head. Associated with certain of the canals 

 and innervated by the same nerves are the ampullary organs, which are confined to the 

 region of the head. Allied to these latter are the pit-organs which are found mainly in 

 the antero-dorsal trunk-region but also on the head. 



Lateral Line Canal on Body. — This organ system in Chlamydoselachus was first 

 described by Carman (1884.1 and 1885.2). In the later article he notes that in the open 

 portions of the lateral canal the margins are formed by a row of flattened scales on each 

 side of the canal, as may be seen in his Fig. 10, pi. VI (our Text-figure 18). This we 

 have verified on our specimens, and particularly on the beautifully preserved head from 

 Columbia University. In a later article (1888), deaHng with the lateral Hne system of 



