12 
SECOND YARKAND MISSION. 
Habitat .—Erom Sind throughout India and Ceylon, and generally ascending mountain 
rivers for the purpose of breeding. Should such rivers he 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 be a synonym of Nemacheilus. 
It is said to consist of <£ elongated fishes, strongly compressed posteriorly,” which we 
perceive in Nemacheilus stoliczkce and N. yarhandensis ; but in an equally elongated species 
N. tenuis , the free portion of the tail is not compressed, but is as wide as deep. 
“The eyes are surrounded with a fold of skin forming a lid.” This is also perceived in 
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. 
“ Lips 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 N. stoliczkce and N. tenuis , have the lips as described by Kessler, the 
N. yarhandensis has not, whilst the three certainly cannot be 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 be very remarkable were 
the Nemcicheili 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 
TJrdjar falling into Lake Ala (Ala-kul), they have the same organ partially free in the 
abdomen, as is seen in genus Botia. But granting Kessler’s description to be accurate, I 
cannot think that such a fact alone would justify instituting a new genus for the reception of 
his species. 
The reason for air-vessels being more or less enclosed in bone 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 Biluridce. 
I found amongst the Indian genera of Siluroids of the fresh waters, or those which entered 
fresh waters, as follows:— 
A. — Air-vessel, when present, free in the abdominal cavity— 
1. llita ; 2. JErethistes ; 3. Bseudeutropius ; 4. 8Hums; 5. Olyra ; 6. Macrones ; 7. 
Callichrous ; 8. Wallago ; 9. Arius ; 10. Hemipimelodus 11. Osteogeniosus; 
12. Bcitrachocephalus; 13. Bangasius ; 14. Blotosus. Of these, five (Nos. 
9, 10, 11,12, and 14) are marine forms, entering fresh waters for predaceous 
purposes. 
B. —Air vessel more or less enclosed in bone— 
1. Ailia ; 2. Ailiichthys ; 3. Sisor ; 4. Bagarius ; 5. Amblyceps ; 6. SaccobrancJms ; 
7. SMundia ; 8. Butropiichthys ; 9. Gagata ; 10. Nangra ; 11. Bseudecheneis ; 
12. JExostoma ; 13. Clarias ; 14. Glyptosternum . All of these are fresh water 
genera. 
1 Memvpimelodus appears to be Arius destitute of teetb on tbe palate. 
