82 THE CHISMOPNEA (CHIMAEROIDS). 
gills, united with the skin distally; opercula rudimentary. Spiracles absent, 
except in certain embryonic stages. Dental laminae in three pairs, vomerine 
and palatine above and mandibular below. Brain massed posteriorly, more 
distributed forward, hemispheres distant from the optic lobes and attached to 
them by a nerve-like thread. Vertebrae imperfect, coalescent anteriorly. 
Sheath of the notochord not segmented. An erectile dorsal fin and spine the 
basalia of which are articulated to a consolidation of the neural spines above the 
pectoral fins. Oviparous. Male on approaching maturity developing claspers 
and a frontal tenaculum and two prepelvie tenacula adapted for clinging to the 
tail and the fins of the female. In some species the wide basal articulation 
of the frontal tenaculum prevents motion laterally and the hooked spines 
below its forward end are met by other sharp spines from within the cradle or 
receptaculum, thus indicating decisively the manner of use and the purpose of 
the organ. Skin naked in adults, a series of small spines, arranged in two rows 
along the middle of the back and on the top of the head, aid the escape from the 
egg shell. 
Snout prominent, soft, without a proboscis 
Brain with olfactories and hemispheres close together 
Notochord surrounded by rings 
Teeth with tritors on their edges 
Claspers of male trifid, rarely bifid. ‘ Chimaeridae 
Snout produced into a long beak 
Brain with olfactories and hemispheres widely separated 
Notochord with rings 
Claspers simple. : : : : : Rhinochimaeridae 
Snout produced into a leaf-shaped, flexible appendage 
Brain with olfactories and hemispheres widely separated 
Notochord without rings 
Teeth with tritors on their sides 
Claspers simple. : ‘ 5 : . Callorynchidae 
CHIMAERIDAE. 
Chimeria Rarinesque, 1815, Anal. Nat., p. 92 (= Chimaera and Mormyrus, = subfam.). 
Chimaerae TuIEN., 1828, Zoologie, p. 412 (= Chimaera and Callorhynchus). 
Chimaeridae Bonap., 1831, Saggio, p. 98, 121 (= Chimaera and Callorhynchus). 
Chimaeridae Garm., 1901, Proc. N. EB. Zool. Club, 2, p. 76 (= Chimaera). 
Head moderately pointed, without a proboscis. Body compressed, taper- 
ing to a point at the tail. Pectoral fins large, free, First dorsal fin short, with 
