488 PHTSOSTOMI. 



head. Uarlch — the maxillary ones reacli tlic opercle or even the base of the pectoral fin : the mandibalar ones 

 equal one diameter of the eye in length. Teeth — villif'orm in the jaws, in a crescentic band across the palate. 

 Fins — dorsal spine weat, roughened anteriorly, finely seiTated posteriorly and as long as the head excluding the 

 snout : pectoral spine stronger, as long as the head behind the angle of the mouth, and reaching to above the 

 ventral. Ventral arises behind the vertical from the last dorsal ray, and reaches to the anal. Caudal forked, 

 the lower lobe rather the longer. Free portion of the tail nearly as high as long. Colours — bluish superiorly, 

 becomiBg white on the sides and beneath, the fins stained externally with gray. 



Sykes says his fish is termed I'urree, Mahr. and SUlun in the Deccan, that it is tvitJiout cirri, and also 

 that the first bony ray is " serrated on the anterior edge," such being also shown in the figui-e. 



The long maxillary barbels of this species serve to distinguish it from S. Gangetica, C.V. 



Habited. — Kivers of the Deccan and the Kistna and Godavery to their terminations. 



B. A 2^air of shoH maxillary barbels only. 



2. Silundia Gangetica, Plate CXIV, fig. 3. 



Timelodus silondia, Ham. Buch. Fish. Ganges, pp. 160, 375, pi. 7, f. 50. 



Silundia Gangetica, Cuv. and Val. xv, p. 49, pi. -126 ; Bleeker, Beng. en Hind. pp. 58 and 118 ; Blyth, 

 Proc. A. S. of Beng. 1858, p. 286 ; Giinther, Catal. v, p. 65 ; Day, Jouru. Linn. Soc. Zool. xii, 1876, p. 569. 

 Silowia lurida, Swainson, Fishes, ii, p. 306. 

 Silond, Punj. : Jil-lung and Silond, Ooriah and Bengal : Wanjou, Telugu. 



B. xi-xii, D. i I 0, P. 1/11-13, V. 6, A. 40-46 (3^*,t), C- l^- 



Length of head 5i, of caudal 5^ to 6, height of body 5 to 5^ in the total length. Eyes — with naiTow 

 anterior and posterior adipose lids, diameter 4 to 4i in the length of head, 1^ to li diameters fi'om the end of 

 snout, and 2 apart. The width of the head equals its length excluding the snout, whilst its height is rather 

 less. Lower jaw the longer, snout rather broad, the width of the gape of the mouth exceeding 1/2 the length 

 of the head. Barbels — a paii- of minute maxillary but no mandibular ones. Teeth — in the jaws villiform, and 

 in a crescentic band across the palate. Fins — dorsal spine rather weak, as long as the head behind the 

 middle of the eye, anteriorly smooth or rugose, posteriorly finely serrated in its upper portion. Pectoral spine 

 stronger, as long as head without the snout, and serrated internally. Ventral arises under the posterior dorsal 

 rays, and nearly reaches the anal. Air-vcsselsmaW, with its lateral edges protected by a short osseous process 

 from either side of the vertebra, but it cannot be said to be enclosed in bone. The air-vessel itself, when opened, 

 is found to consist of two oval chambers, having a communicating canal, and in the young is almost surrounded 

 by high osseous sides. Colours — bluish along the back, becoming silvery on the sides, fins stained with gray. 



Habitat. — Estuaries of India and Bm-ma, ascending high up the larger rivers to nearly their sources. It 

 attains 6 feet or more in length, and is called " a shark" by the natives. It is very voracious. 



Genus, 20 — Ailia, Gray. 



Branchiostegals eight. Gill-openings wide, the gill-membranes not confluent with the shin of the istlimus. 

 Body elongated and strongly comjrressed. Head covered ivith thin shin. Eyes nearly or quite behind the angle of the 

 mouth, and with adipose lids. Upper jato slightly the longer. Nostrils patent, those on either side appro-timating, 

 the anterior in front of the snout. Eight barbels. Villiform teeth in thejaivs and in two minute patches on the vomer. 

 No anterior,* but a small adipose dorsal fin posteriorly. Pectoral with a spine. Ventral with six rays. Anal long 

 (59-75 rays). Caudal forked. Air-vessel tuhiform, lying across the body of an anterior vertebra, from xvhich it is 

 separated by the aorta, whilst externally it is protected by bone. No axillary pore. 



Geographical distribution. — Sind, the larger rivers of the Punjab, N. W. Prov. Bengal, Assam and 

 Orissa. 



SYNOPSIS OF INDIVIDUAL SPECIES. 



1. Ailia coila, V. 6, A. 59-75. Silvery, fins usually -n-ith dark edges. Indus, Jumna, Ganges, Brahma- 

 putra, and Mahanuddee rivers. 



1. Ailia coila, Plate CXIV, fig. 4. 



Malaptermus coila. Ham. Buch. Fish. Ganges, pp. 158, 375. 



Silurus (Acatlwnotus) Cuvieri, Gray and Hard. Ind. Zool. 



Malapterus (Ailia) Benqalensis, Gray and Hard. Ind. Zool. ; Swainson, Fishes, ii, p. 307. 



Ailia Bengalensis, Gray, Zool. Misc. 1831, p. 8 ; Cuv. and Val. xv, p. 538 ; Giinther, Catal. v, p. 56. 



Acanthoncitus Hardwiclcii, Gray, Zool. Misc. 1831, p. 8. 



Melapterurus Cuvieri, Swainson, Fishes, ii, p. 307. 



* In some specimens there is a small basal bone situated on the back anterior to the vertical from the origin of the ventral fin, 

 otherwise I cannot discover a vesiige of the first dorsal fiu. However, Dr. Uiinther has discerned ■■ a small hole in the skin where the 

 dorsal fin ought to have been placed, it is a short distance from the occiput, and a Uttle before the vertical from the ventral fins," Catal. v, 

 p. 55. 



