A REVISION OP THE BRANOHIOSTOMID^. * 315 



fessorBaldwin Spencer were iu an excellent state of preservation. 

 They all show a greater compression of the body from side to 

 side, i. e. less thickness, than do similar specimens of Amphi- 

 oxus lanceolatus. 



Although the gonad pouches develop on the right epipleur, 

 they extend when ripening across the median line of the body, 

 so as to be visible through the left epipleur. 



2. Heteropleuron cingalense, n. sp., PI. 35, fig. 7. 



Myotomes, maximum number 64, minimum number 61 

 (iu eight specimens, J. W. K.). 



Myotome formula 39, 17, 6; 39, 17, 8; 39, 16, 8; 38, 17, 8. 



Dorsal fin low (one eighth of height from crest of fin to edge 

 of metapleur at mid-body). Rostral fin small, not marked ofi" 

 from dorsal fin. Ventral fin with fin-ray chambers and paired 

 fin-rays. Oral sphincter underlies the apex of the fourth myo- 

 tome. Intra-buccal cirrhi not determined. Gonad pouches 

 twenty-five, only present on the right epipleur. 



Maximum length of eight specimens 3 cm. (J. W. K.). 



Distribution. — Coast of Ceylon. 



Hem arks. — Four of the specimens examined by me were 

 collected by Mr. Haly, and supplied to Professor Lankester by 

 Professor Haddon. Three of these gave the myotome formulae 

 39, 17, 8; one (that figured) gave 39, 17, 6. Five specimens 

 were lent to Professor Lankester by Professor Good Brown 

 from the United States National Museum. Of these, one 

 appears not to belong to this species at all, and, in fact, belongs 

 to the sub-genus Amphioxus. The remaining four presented 

 the myotome formula 39, 16, 8; 38, 17, 8; and 37, 15, 9. 

 From these facts I think it is clear that there is a Cingalese 

 Heteropleuron distinct from H. Bassanum, from which it 

 diff'ers chiefly in its smaller number of myotomes. Whether 

 the specimen of Amphioxus included amongst the specimens 

 sent from the United States National Museum indicates a 

 distinct Cingalese species of the sub-genus Amphioxus, or is 

 referable to A. Belch eri, I prefer to leave an open question. 



