192 THE ZOOLOGIST. 



lower part. The place of the upper pharyngeal teeth is occupied 

 by ribbed mucous membrane. 



OSTRACIONTID^. 



Ostracion gibbosus, one of the Trunk fishes, so-called from 

 the horny, rigid case that envelopes them ; this specimen came 

 from the Indian Ocean. It has eight short, horny, upstanding 

 gill-rakers on the outside of the first branchial arch. There 

 are only four of these arches. On the inner side of the first 

 arch there are twelve gill-rakers, similar to those on the outer 

 side. The other arches bear gill-rakers, and they all form a close 

 filter. The gill-laminae are long for the size of the fish, and the 

 longest of them in depth is some six times the length of the 

 longest gill-raker. There are no pharyngeal teeth discernible, 

 either upper or lower. 



Ostracion nasus has nine short, horny, upstanding gill- 

 rakers on the outside of the first branchial arch, with fifteen 

 on the inner side. No pharyngeal teeth discernible. 



Tetrodontid^. 



Tetrodon leopardus, one of the "Puffers" or Globe-fishes, 

 so called from their being able to puff themselves out with air 

 till they assume a globular appearance. This specimen came 

 from the Indian Ocean. It has ten soft gill-rakers on the first 

 branchial arch, seven being on the cerato-hypobranchial portion, 

 and three on the epibranchial. The other arches have tubercles 

 on them that stand out distinctly. There are only three gill arches 

 in this fish on each side. There are no pharyngeal teeth. The 

 mucous membrane of the mouth at the back is divided into three 

 distinct sections on the site usually occupied by the pharyngeal 

 teeth in other fishes. The upper section is covered with corru- 

 gations that run in an up-and-down direction ; the other sections 

 have minute papillae. Nothing but lining mucous membrane is 

 observable on the floor of the gullet. 



Tetrodon reticularis, from the Indian Ocean, has thirteen soft, 

 papillse-like gill-rakers on the first cerato-hypobranchial, not 

 growing in a defined row, but scattered along it ; some are 

 longer than the others. On the inner side of the first arch and 

 on the other arches there are the same kind of gill-rakers 



