12 
SECOND YARKAND MISSION. 
Habitat. — Erom Sind throughout India and Ceylon, and generally ascending mountain 
rivers for the purpose of breeding. Should such rivers be snow-fed, it deposits its ova in the 
side streams. 
Before describing the Loaches, I will give my reasons why it appears to me that the 
genus Biplophysa, Kessler, may probably he a synonym of Nemacheilus. 
It is said to consist of “ elongated fishes, strongly compressed posteriorly,” which we 
perceive in Nemacheilus stoliczkce and N. yarkandensis ; but in an equally elongated species 
N. tenuis , the free portion of the tail is not compressed, hut is as wide as deep. 
“ The eyes are surrounded with a fold of skin forming a lid.” This is also perceived m 
specimens amongst the species I have enumerated from Yarkand ; and I have likewise noted 
that some of the other fishes from the same cold region have folds of skin more or less cover- 
ing the eyes. 
“ Dips fleshy, the upper more or less denticulated, the inferior bilobed, and more or less 
papillated.” I have figured the inferior surface of the head of all the Loaches; and 
although some, as A T . stoliczkce and N. tenuis , have the lips as described by Kessler, the 
N. yarkandensis has not, whilst the three certainly cannot he separated into distinct genera. 
“ Air-vessel in two parts, the anterior enclosed in a bony capsule, the posterior elongated 
and free in the abdominal cavity.” This is the only portion of Kessler’s definition not perceived 
in these fishes in which the air-vessel is enclosed in bone ; and I cannot resist suggest- 
ing a re-examination of Western Turkestan specimens. It would bo very remarkable were 
the Nemacheili found in Europe, in fact throughout Asia, even in the Oxus, to have their 
air-vessels enclosed in bone, whereas in the river Hi going to Lake Balkash, and the river 
Urdjar falling into Lake Ala (Ala-kul), they have the same organ partially free in th e 
abdomen, as is seen in genus Bolia. But granting Kessler’s description to be accurate, 1 
cannot think that such a fact alone would justify instituting a new genus for the reception or 
his species. 
The reason for air-vessels being more or less enclosed in hone in some fishes is obscure ; 
and I some time since adverted, in the ‘ Proceedings of the Zoological Society,’ to the circum- 
stance of such not being infrequent in Indian Siluridce. 
I found amongst the Indian genera of Siluroids of the fresh waters, or those which enterec 
fresh waters, as follows : — 
A. — Air-vessel, when present, free in the abdominal cavity — 
1. Rita ; 2. Erethistes ; 3. Pseudeutropius ; 4. Silurus ; 5. Olyra ; 6. Macrones ; * 
Ccillichrous ; 8. Wallago ; 9. Arius ; 10. Hemipimelodus ; l 11. Osteogeniosu s > 
12. JBatrachocephalus ; 13. Pmgasius ; 14. Plotosus. Of these, five (^ oS ‘ 
9, 10, 11, 12, and 14) are marine forms, entering fresh waters for predaceous 
purposes. 
JB . — Air vessel more or less enclosed in bone — 
1. Ailia ; 2. Ailiichthys ; 3. Sisor ; 4. Bagarms ; 5. Amblyceps ; 6. Saccobranchus , 
7. Silundia ; 8. Eutropiichthys ; 9. Gagata ; 10. Nangra ; 11. Pseudecheneis > 
12. Exostoma ; 13. Glorias; 14. Glyptosternum. All of these are fresh w a 01 
genera. 
1 Hemipimelodus appears to be Arius destitute of teetb on the palate. 
