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in form as well as in their number and arrangement. In jaws 

 in one or more series. On vomer in one to three series or in 

 a group; on intermaxillary plate in a semicircle, enclosing a 

 few larger central ones, or in a group. Gillopcnings small, 

 horizontal, situated in the middle of the height of the body. 

 Distribution: Reefs and shores of tropical seas. 



Artificial key to the indo-australian species 

 of Echidna. 



A. Tail twice or more tlian twice in head and trunk. 

 Roundish group on intermaxillary plate and pear- 

 shaped group of vomerine teeth continuous. Blackish 



brown with 30 to more tlian 100 narrow white rings. E. zebra p. 345. 



B. Tail equal to, '/s longer or somewhat shorter than 

 head and trunk. 



I. 24 — 29 narrow rings, exceptionally on tail only. 

 When young, teeth on intermaxillary plate in a 

 peripheral series enclosing 3 larger mesial ones , 

 on the vomer in 2 series; when old, on intermaxil- 

 lary plate and on vomer in a group E. polyzoiia p. 346. 



II. Spotted. Origin of dorsal before gillopenings. Teeth 

 on intermaxillary plate in a semicircle with i or 2 

 central ones. Tail somewhat shorter than head 

 and trunk. 



1. Brown with numerous round or oval patches. 



Head less than thrice in trunk E. xanlhospilus p. 348. 



2. Numerous small spots or lines and 2 series of 

 large, more or less star-like patches. Head s'/a 



to more than 4 times in trunk E. lubtilosa p. 348. 



III. Uniform with white spot near corner of mouth. 



Origin of dorsal above or behind gillopenings. . . E. ihodochilus p. 350. 



IV. Marbled or mottled with darker. Origin of dorsal 

 before gillopenings. 



1. Origin of dorsal far before gillopenings. Teeth 

 on intermaxillary plate in a semicircle, enclosing 



2 strong teeth in middle; on vomer in 2 series. E. JeUcalula p. 350. 



2. Origin of dorsal shortly before gillopenings. Teeth 

 on intermaxillary plate in a group; on vomer 



in a single series E. aniblyoJon p. 351. 



I. Echidna zebra (Shaw). [Fig. 168, p. 344]. 



Gymnolhora.x zebra Shaw, Natural. Miscell. IX. 1797, pi. 322. 

 Gyiiiiwthorax zebra Bloch, Schneider, Syst. Ichih. iSoi, p. 528. 



