Mr. G. A. Boulenger on the Genus Pseudoxyrhopus. 311 
which is twice the length of the eye or \ the total length of 
the head, and conspicuously prominent beyond the mouth. 
Eyes circular, set high up on the side of the head, deep 
beneath a small transparent area of skin, a diameter and a 
half apart. 
Anterior nostril a short wide tube situated inferiorly at the 
tip of the snout. Posterior nostril a large circular foramen 
just above the anterior orbital angle. 
Mouth subrostral ; its angle reaching slightly behind the 
vertical through the anterior border of the orbit; the jaws 
completely hidden by the very thick inflated lips. Villiform 
teeth in broad bands in the jaws, and in a broad, confluent, 
triangular patch covering the palate. Tongue free. 
Gill-openings small, widely separated foramina, hardly 
larger than the eye ; four gills with narrow laminse and coarse 
lamellae and wide clefts ; no gill-rakers. 
Integument thick, coriaceous, scaleless, investing the 
vertical fins and completely concealing their rays. The lateral 
line traverses the middle of the body. 
Vertical fins confluent ; the dorsal begins a distance behind 
the occiput equal to the length of the postrostral portion of 
the head, or just behind the level of the tips of the pectorals 
when laid full back. The anal begins immediately behind 
the vent. Pectorals small, pointed, equal in length to the 
rostrorbital portion of the head. 
Stomach with a cul-de-sac of moderate size ; intestine wide, 
little convoluted ; liver large, indistinctly lobated, embracing 
the oesophagus. Air-bladder very large, with very thick 
spongy walls and a small central cavity. 
Colours in the fresh state Body and fins uniform purple- 
black. 
One female specimen, 17 inches long, with mature ovaries. 
Station 104, 1000 fathoms. 
I am greatly indebted to Professor Wood-Mason for 
counsel and advice. 
XXXV. — On the Ophidian Genus Pseudoxyrhopus, Gthr. 
By G. A. Boulenger. 
A CURIOUS snake from Madagascar was described by Jan in 
1863 under the name of Homalocephalus, which name, being 
preoccupied in entomology, was changed by Gunther to 
Pseudoxyrhopus in 1881. Jan placed his new genus among 
22 * 
