2G8 Capt. A. C. MacGilchri:^t on a 



in(li>tinctiy serrated, those of tlic larj^er are coarsely dentate- 

 JSurfacc of elielipcds (except fingers) is finely granular and 

 the margins of arm and wrist are fringed with long hairs. 



Tlie first three pairs of ambulatory legs are slender, com- 

 pressed, have a finely granular surface as far as the merus 

 (inclusive), and end in sabre shaped dactyli ; carpopodites 

 and propodites are fringed Mith long liairs. The fourth or 

 last pair of legs are small, subdorsal in position, and arise 

 near the middle line of the bcdy. 



The abdomen of the male consists of five separate segments 

 — third, fourth, and fifth being fused — and has a finely 

 granular surface. The abdomen corresponds very closely 

 Avith that of P. notojjus, even to the crescentic ridge on the 

 sixth segment. Its breadth opposite the penultimate pair of 

 legs is aliout a third of the breadth of the sternum at the 

 same point. The genital ducts open as in P. nolopvs. 



Only a single specimen, and of the above dimensions, vias 

 obtained, trawled at Sta. 332, south-east of South Andaman 

 Island, 279 fathoms. 



This specimen is of special interest, as it adds a second 

 species to the hitherto solitary species — P. notopus — of the 

 family Ptenoplacif'ae of the Indian fauna. The two species 

 resemble each other closely, but difl'er markedly in the 

 following points: — The sculpture and outline of the front 

 and carapace, especially the antero-latcral borders and the 

 transverse sutures of the carapace ; the orbits ; the relative 

 lengtlis of the eyes, the second and basal joints of the 

 antennules. 



Has been figured for " Illustrations of the Zoology of 

 II. I. M.S. ' Investigator.' " 



XXVIII. — Natural History Notes from the R.I. M.S. 'Investi- 

 gator' Capt. T. H. Heming, RN. {retired), commanding. — 

 Series III., No. 8. On a new Genus of Tcleostean Fish 

 closely allied to Chiasmodus. ]5y A. C. jMacGilchrist, 

 M.A., M.B., Ch.l3., Capt. I.M.S', Surgeon-Naturalist to 

 the Marine Survey. 



Suborder Percesocks (Boulenger) . 



Fam. Chiasmodontidie, Gill. 



Dysalotns Alcocki, gen. et sp. n. 



B. 7. D. VIII. 27. A. 27. P. 11. V. I, 5. 



The body is elongate and compressed j its height contained 



