i6 



CHBLEROID FISHES AND THEIR DEVELOPMENT. 



MOVEMENTS. 



C/iniKii-a collici is essentially a delicate fish. When taken from the water it 

 struggles but little and soon dies (about 15 minutes). It makes no sound, save on 

 rare occasions, when it clicks its dental plates together ; and it shows no effort to 

 erect its dorsal spine. In handling it the fishermen take less account of the formi- 

 dable spine than of the jaws, which are capable of inflicting a painful wound, in one 

 case snapping out at a single stroke a bit of skin and flesh. It is a difficult fish to 

 keep alive, even under favorable conditions. In the aquarium of the Hopkins Sta- 

 tion it lived rarelv longer than two days.* 



Fig. 4. — Chimaera colliei. Sketches ot the hving fish. 



A. Swimming fish shown from in h"ont. This indicates particularly the position of the pectoral fins; from the point marked with an asterisk (*) 

 undulations arise which pass out over the tip of the fin as indicated by the arrows and end at the fin's posterior margin. 



B. Fish shown in resting position. The tail droops somewhat and the weight of the trunk is apt to fall upon the fleshy pad which is present on 

 the ventral side of the body immediately behind the mixipterygia. The opening of the operculum and the position of the mouth in this, as in the pre- 

 ceding figure, are indicated in their normal position. 



C. Mouth region, showing the extent to which the jaws open during the process of breathing. As here shown, the opening is even greater than 

 usual. Behind the mandibular plates can be seen the wide breathing valve 6 r, and the prominent anterior nostrils. The latter serve to pass water 

 lateralward under the large labial folds into the mouth. 



The moving fish is conspicuous in the use of its paired fins. The pectorals are 

 in constant motion, like delicate translucent fansf moving to and from the bod\', 

 and passing undulations one after another along their delicate rims, somewhat 

 as in the pectorals of skates. Thus, in the sketch given in fig. 4 a, these fins are 

 seen in a characteristic position. They are supposed to be moving dorso-ventrad, 

 the path of their flexible tips describing an arc of about 90°. At the ventralmost 



*Mr. C. F. Holder, the director of the aquarium at Avalon, Santa Catalina Islands, informs the writer that he 

 has been able to keep t'. collici alive for a longer time, although no definite time was recalled. 



fXhe translucency of the pectoral fins is seen in the photograph reproduced in fig. i, page ii. 



