Mr. (t. a. Boulengero/i npio Fishes from Sarawak. 247 



contains a single case of uljuorniality by reversion to a simple 

 type of limb occurring in one of the mouth-appendages of a 

 specimen of Platycarcinus pagurus. Those of the second class 

 are cases of " monstruositc par exces : " they are usually con- 

 fined to the chela ; but in such cases the limb is more or 

 less functional. Possibly the example described above is 

 unique. 



XXXI. — Descriptions of Two new Fishes obtained hi/ Mr. G. 

 Hose in Sarawak. By G. A. Boulexgkr, F.R.S. 



Plotosus ahbreviatus. 



Band of teeth in each premaxillary thrice as broad as 

 long ; vomerine teeth large, molar-like, in a large crescentic 

 patch ; a broad band of molar-like mandibular teeth, with an 

 outer series of large obtusely conical ones. Dejith of body 

 8 times in total length, length of head 4 times. Head 1^ as 

 long as broad, its deptli 'j^ its width ; diameter of eye 11 times 

 in length of head, 3^ times in interorbital width ; nasal barbel 

 extending to praopercle, maxillary barbel to opercle. First 

 dorsal 1 4, its depth f length of head; confluent dorsal, anal, 

 and caudal with 190 rays (D. 90 ; C. 18 ; A. 82). Pectoral 

 with 12 soft rays, ventral with 14 ; pectoral s|)ine a little 

 longer than dorsal, f length of head. Uniform dark olive 

 above, whitish beneath. 



Total length 420 millim. 



A single specimen, from the mouth of the Baram River. 



Rasbora Hosii. 



Depth of body 3^ to 3^ times in total length, length of 

 head 4 times. Snout as long as diameter of eye, 3^ times 

 in length of head ; interorbital width half length of head ; no 

 barbels. Dorsal II 7, originating a little nearer base of 

 caudal fin than end of snout, nearer to base of ventrals than 

 to origin of anal fin, and opposite to the eleventh scale of the 

 lateral line. Anal II 5. Pectoral nearly as long as head, 

 not reaching ventral. Scales 28-29 p ; one scale between 

 lateral line and base of ventral. Caudal as long as head. 

 Olive above, silvery beneath, the dorsal and lateral scales 

 with a blackish edge ; caudal edged with blackish. 



Total length 110 millim. 



Two specimens, from the Baram Kivcr. 



