GLYPHIDODONTIDJE. 



379 



Colour black or chestnut-brown, fins black-edged. A broad white 

 band margined with black passes over occiput and on to opercles ; 

 a second from last three dorsal spines to in front of base of anal ; 

 a third over free portion of caudal. 



Fig. 126. Premnas biaculeatus. 



This fish sometimes uses Actiniae as a hiding-place (De Cresp. 

 P. Z. S. 1869, p. 248). 



Hab. Seas of India to the Malay Archipelago and beyond. 



3. Genus TETRADRACHMUM, Cantor. 

 Syn. Dascyllus, Cuv. (Preoccupied by Latreiile (1796), Coleoptera.) 



Branchiostegals five. Preopercle, and occasionally the preorbital, 

 serrated. Teeth villiform in a narrow band, the outer row some- 

 what larger. Dorsal with 12 or 13, anal with 2 spines. Scales 

 large or of moderate size. Lateral line ceases in a tubular form 

 below the soft dorsal, but is continued along the middle row of 

 scales as a circular hole in each. Air-bladder large. Pyloric 

 appendages two or three. 



Geographical Distribution. Indo-Pacific Ocean. 



Synopsis of Indian Species. 



Brown, vertical fins dark 1. T. trimaculatum, p. 379. 



Bluish, many scales with a bright blue spot . 2. T. marymatum, p. 380. 

 Pearl-white, with 3 vertical black bands . . 3. T. aruanum, p. 380. 



1223. (1.) Tetradrachmum trimaculatum. 



Pomacentrus trimaculatus, Rupp. Atl. Fische, p. 39, pi. viii, fig. 3. 

 Tetradrachmum trimaculatum, Day, Fish. India, Suppl. 1888, p. 801 

 (see synon.). 



D. 12/13-15. A.2/13-14. L.1.27. L.tr.3/11. C.p.3. Vert. 11/14. 



