318 SECTIONAL TRANSACTIONS.—C, D. 
The following exhibits were arranged during the meeting :— 
(a) Geological maps and photographs of the Southampton District and 
Isle of Wight. By Sir J. 8. Frert, F.R.S. 
(b) Rocks and vein specimens to illustrate the Cornish mining industry. 
By Mr. E. H. Davison. 
(c) Bones and Scutes of an armoured Dinosaur from Southern India. 
Exhibited by Dr. C. A. Matiey. 
(d) Trilobites from China. Exhibited by Mr. B. Hitton Barrerr. 
SECTION D.—ZOOLOGY. 
(For references to the publication elsewhere of communications entered in the 
following list of transactions, see page 389.) 
Thursday, August 27. 
Mornine. 
1. Mr. B. K. Das.—The Biology of the Post-Larval Development of some 
Air-breathing Fishes of India. 
Broadly speaking, six Indian genera of air-breathing fishes (out of which five 
principal types have been brought over here alive), comprising nine species, are being 
discussed in the present paper. They are as follows: (1) Clarias (the Indian Cat-fish) 
and (2) Saccobranchus (* Scorpion ’-fish)—both belonging to the fam. Clariidse—order 
Siluroidea ; (3) Anabas (the so-called * Climbing ’ Perch of India), and (4) Macropodus 
(fam. Anabantidee—order Labyrinthici); (5) Ophiocephalus (Murral—fam. Ophio- 
cephalide—order Labyrinthici), and (6) Amphipnous (Cuchia ‘ eel ’—fam. Amphi- 
pnoide—order Symbranchii). These fishes are remarkable in being able to live not 
only in water, but also out of water for a considerable length of time, and they often 
migrate long distances from one pond to another. They breathe pure air, and are 
often observed coming to the surface of the aquarium to swallow atmospheric air ; if 
they are prevented from so doing, they become asphyxiated and ‘drowned.’ They 
do quite well in muddy water, but cannot survive for any considerable time in pure 
water, if they are cut off from direct access to atmospheric air, no matter how fully 
the water may be oxygenated. 
The air swallowed passes backwards from the mouth cavity into certain peculiar 
“ air-reservoirs,’ usually situated posteriorly in the cephalic region. The used up gas 
is generally expelled from the opercular chamber. Curiously enough, these reservoirs 
vary both in structure and mode of development in the various types enumerated 
above. Thus in the Indian Cat-fish (Clarias) the air-reservoir is situated above the 
gill-arches on each side of the head and lodges a pair of highly vascular .air-breathing 
“trees ’’ borne on the second and fourth branchial arches; in Saccobranchus it is a 
tubular sac (richly supplied with blood) extending from the region of the gills to 
about three-quarters of the length of the fish, and situated on either side of the 
vertebral column buried within the adjacent muscles ; in Ophiocephalus it is a large 
highly vascularised chamber (the walls of which may be simple and smooth, or greatly 
folded) situated on the under-surface of the skull at its posterior end, above the 
branchial region. The air-breathing organs of Anabas and Macropodus consist of an 
air-chamber situated on either side of the skull, above the first gill-arch, from 
which peculiarly modified ‘ shelly ’ plates (most elaborate in Anabas) extend into its 
cavity. In Amphipnous the accessory breathing organs have reached their highest 
stage of perfection. In these the gills have practically atrophied, and the accessory 
organs are in the form of a couple of bladders (* lungs ’) situated behind the head region. 
They really perform the principal role in respiratory functions. 
These accessory air-reservoirs may either be developed as special modifications of 
the opercular chamber (Clarias, Saccobranchus, Anabas, and Macropodus), or merely 
as dorsal out-growths from the pharyngeal cavity (Ophiocephalus and Amphipnous). 
They bear no relationship to the air-bladder of other teleosts. Thus, the typical 
air-bladder characteristic of the sub-class Teleostei may be well developed and persist 
