270 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
he put his order 8, Plagiostomi (Selacii), Family 34, Squalidae, and Family 35, 
Rajidae, and his order 9, Cyclostomi, Family 36, Petromyzonidae. The same 
objections apply in the case of his order Acanthorrhini as in that of Latreille’s, 
Family Acanthorhina. 
Miiller, 1834-35, settled the question of priority so far as concerned him by a 
name of his own, Holocephala. He included in this order only Thienemann’s 
1828, Family Chimaerae, Bonaparte’s, 1831, Chimaeridae, containing the two 
genera discovered in 1754. The new name was supposed to be more appro- 
priate for these Chondropterygii on account of the suspensorial connections of 
the lower jaws. However, if it be taken into consideration that the rostral 
cartilages of the Antacea, Sharks, and of the Platosomia, Skates and Rays, are 
outgrowths of the skull, and not articulated to it, while the same cartilages of 
the Chimaeroids are articulations, and not solid outgrowths from the skull, it 
will appear that the term Holocephala would be quite as appropriate for 
Plagiostomia as for Chismopnea. 
The living Chimaeroids may be classified as below. 
CHISMOPNEA Rar., 1815. 
Chismopnés Dum., 1806. 
Holocephala Miill., 1884. 
Chondropterygii, with a compressed and massive body, an attenuated caudal 
region, a single external branchial cleft on each side, an erectile first dorsal 
spine and fin, a cartilaginous skeleton, a notochord not divided in vertebrae, a 
brain in which the hemispheres are remote from the optic lobes, a rostrum of 
which the cartilages are articulated to the skull, a dentition of two pairs of 
upper and one pair of lower dental plates, a frontal tenaculum, ventral tenac- 
ula and claspers on the male, and without distinct suspensorial cartilages for 
the lower jaws, without shagreen on the skin and without a diverticular gland 
on the intestine. Oviparous, the egg deposited in a horny case. 
RHINOCHIMAERIDAE Garm., 1901. 
Chismopnea, with an elongate, pointed, movable proboscis, with olfactory bulbs 
and hemispheres of the brain remote from one another, with a notochord sur- 
rounded by narrow cartilaginous rings, with a simple cartilage in each clasper 
of the male, and with subtubular lateral canals opening outward through a 
narrow slit. At present this family contains two genera of a single species 
each. 
Species with compressed proboscis and having teeth with cutting edges and 
without tritors on the sides of the plates. 
thinochimaera pacifica Mits.; Garm., 1901. 
