FAMILY, II— SQUAMIPINNES. 103 



First group — Chatodontina, 

 No palatine or vomerine teeth: no concealed spine in front of the base of the dorsal fin in the adult. 



Genus, 1 — Ch^todon, Giw. 



Babdophorus and Miarocanthus, Swains. ; Megraiprotodon, Guich. ; Sa/rothodus, Gill. 



BramoMostegals six. Body elevated and strongly compressed. Snout of moderate length, or short. Pre- 

 opercle entire, or slightly serrated, but destitute of amy spine at the angle. Palate edentulous. Spinous and soft 

 portions of the dorsal fm not separated by a notch, the rays of slightly or considerably loA-ger mwmber than the spines, 

 none of the latter elongated: amal with three or four spines. Scales of large, moderate, or small size. Lateral line 

 continuous, sometimes incomplete. Air-vessel may be constricted or with horns. Intestines much convoluted. 



SYNOPSIS OP SPECIES. 



A. With four anal spines. 



1. Chmtodon plebeius. D. rr-TT. -*■• tt-tT) L. 1. 50. A black ocular band with white edges : a black 

 white-edged ocellus at the base of the caudal fin. Andamans to the South Seas. 



B. With three anal spines. 



2. Chcstodon xamthocephalus. D. »f , A. ^\, L. 1. 38. A small dark blotch above the orbit : body with 

 five indistinct vertical streaks. Ceylon and Zanzibar. 



3. Chcdodon falcula. D. ^Z^, A. -sy^.^sj L. r. 28. A narrow ocular band, two wide triangular bands 

 pass downwards from the dorsal fin, another exists over the free portion of the tail. Twelve or more narrow 

 black bands on the body. Seas of India to the Malay Archipelago and beyond. 



4. Ohmtodon pictus. D. i|, A. 2^!2^, L. r. |f . An ocular band descending to the chest. Several dark 

 lines descend downwards and forwards from the first half of the dorsal fin to the head, whilst in the last half 

 of the body others go backwards and downwards. Dorsal and anal fins dark : caudal with a dark base and two 

 dark vertical bands. Red Sea, seas' of India, to the Malay Archipelago. 



5. Chmtodon vagabwndMS. D. -Ullf , A. -^l-^, L. r. ff. An ocular band descending to the interopercle. 

 Many dark bands pass downwards to the middle of the body when they go backwards. Dorsal and anal fins 

 margined with black : two vertical black bands on caudal. Prom the Red Sea throughout those of India to 

 Polynesia. 



6. Ohcetodon Mertensii, D. I-J, A. -5^, L. 1. 34. A narrow interrupted ocular band : anterior two-thirds of 

 body violet, with narrow vertical, angular, bands : last third of body, soft dorsal, and anal fins yellow : a vertical 

 band on caudal : a narrow dark intramarginal line to soft dorsal and anal fins. Red Sea, Seas of India, and 

 beyond. 



7. Chmtodon auriga. D. -5-^:^4, A. yo-ttj L. 1. 42. Fifth dorsal ray prolonged. An ocular band descends 

 to the interopercle. A dark ocellus on the middle dorsal rays. Red Sea, through those of India to Polynesia. 



8. Chcetodon EJeinii. D. 2-I-I-5, A. rs-^Ti ^- 1- 33. Brownish, with a broad ocular band extending to a 

 black ventral fin : edges of soft dorsal, caudal, and anal black. Seas of India to the Malay Archipelago. 



9. Chcetodon guttatissimus, D. ■^, A. rr-Ts) ■'-'• h 38. An ocular band descends to the interopercle : brown 

 spots on the body scales, and small ones on the soft dorsal and anal fins : caudal with a black vertical band. 



10. Chcetodon ^ittatus, D. ar-T?) -^- A> -'-'■ ^- tf- Body with numerous fine dark lines passing backwards : 

 a dark band along the base of the dorsal fin, another along the centre of the soft dorsal : a dark band on the last 

 third of the caudal : ventrals white. From the Red Sea to Polynesia. 



11. Chcetodon mwnaculatus, D. a^-l-s, A. To-a-g-, L- 1- 46. A narrow ocular band : a black blotch on the 

 side above the lateral-line beneath the last four dorsal spines. Ceylon to the Malay Archipelago. 



12. Ghmtodon eollaris, D. a-f-TTj -^^ a^-T2i ^- h 34. Each scale with a light centre : a whitish band from 

 in front of the dorsal fin to the chest, another to the eye, and a third over the snout. Seas of India to the 

 Malay Archipelago. 



13. Chcetodon lunula, D. -g^-l-g-) A. T8-?a-oi L- h 40. A wide ocular band descends to the preopercle : a 

 second from the first dorsal spine joins it : a third goes to the base of the pectoral, and another over the free 



Tholichtliys osseus, PI. XXVI, fig. 2 (twice life size.) 

 Day, Proc. Zool. Soc. 1870, p. 687. 



D. Ih P. 15, V. 1/6, A. T9?iio. C. 17, L. 1. 41. 



Length of head nearly 1/3, of caudal 1/5, height of body 1/2 of the total length. Hyes — diameter from 1/2 to 2/5 of the 

 length of head, 1/2 in diameter, from the end of snout, and 1 apart. In the specimen figured the angle of the preopercle is much enlarged, 

 reaching to almost below the origin of the pectoral fin : the shoulder scale and those over the shoulder girdle considerably dilated. 

 Fins — third dorsal spine the longest and strongest, the fin notched : ventrals rounded : caudal cut almost square. Scales — ctenoid. 

 Lateral Une — ceases opposite the end of the soft dorsal fin. 



This is evidently the same species as the one I formerly described, Z. c. but the development of the cranial bones differs. Pro- 

 bably in Holaccmthi the preopercular spine is the remains of the elongated and dilated preopercular angle seen in this species. 



In the very young, as figured by Dr. Giinther, the developments mentioned above are greatly magnified, showing that atrophy 

 occurs as age advanccSf 



