BORRADAILE— ON CARIDES FROM THE WESTERN INDIAN OCEAN 405 



Miladumadulu Atoll (Gardiner's Fauna of the Maldives, i. p. 98). In the case of the 

 Miladumadulu species the habits and appearance of the prawns in the living state 

 enabled the two forms to be distinguished with certainty. Possibly similar information 

 would avail in the same way here. 



Subfamily Pontoniin^. 



Many species of this subfamily are represented in the collection.- They are 

 enumerated in a separate article in this volume (pp. 323 — 396). 



Superfamily Crangonoida. 



The bounds of this somewhat miscellaneous group must be enlarged to admit 

 the genera Anchistioides, Amphipalcemon, and Hymenocera, which, in our present state 

 of knowledge appear more closely related here than elsewhere. This addition involves 

 two concessions in the definition of the group : (l) [{Anchistioides and AmphipalcBmo7i 

 are to be admitted, it can no longer be stated that the mandible is always without 

 incisor process, (2) the inclusion of Hymenocera makes it necessary to allow the 

 persistence of a small representative of the second lobe of the maxilla. 



Family Anchistioidid^. 



Borradaile, Ann. Mag. Nat. Hist. (8), xv. p. 205 (1915). 



In 1899, reporting on the Macrura brought by Dr A. Willey from the South Seas, 

 I established a genus Palcemonopsis for a new prawn, P. willeyi, taken in New Britain. 

 In 1901, Nobili proposed to change the name of this genus to AmphipalcBmon, on the 

 ground that Palcemonopsis was preoccupied, having been used by Stimpson as a 

 synonymn of Palcemonetes. Both by Nobili and by myself the genus has been regarded 

 as belonging to the Paleemonidse. 



The present collection contains two specimens, each representing a new species 

 of Amphipalcemon. Examination of these, and re-examination of Dr Willey's original 

 specimen, convinces me (l) that the characters of the new genus are so distinctive 

 that it must become the type of a new family, (2) that the affinities of this family 

 are at least as much with the Crangonoida as with the Palsemonoida, (3) that the 

 genus Anchistioides founded by Paulson in 1875 is closely related to Am,phipalcBmon. 



The characters of the AnchistioididsB may be stated as follows : 



(1) The body retains the typical caridoid facies. 



(2) The rostrum is well developed, compressed, and toothed. 



(3) There is no supraorbital spine, but there may be a blunt knob nearly in 

 the same position. 



(4) The outer flagellum of the antennida bears at the base a short, thick, 

 accessory flageUum. The stylocerite is inconspicuous or wanting. 



