DR WILLEY FROM THE SOUTH SEAS. 401 



shaped middle keel ; but neither are the outer angles of the rostrum sharp, and the 

 keels of the sabmedian telson-spines do not converge forwards. Should a name for 

 this variety be thought necessary, it is here proposed to call it var. anancyrus. 



To these three varieties may be added that distinguished by Pocock in 1893 

 {loc. cit.) under the name of G. smithii, and characterised as follows': — 



1. The keels of the sixth abdominal segment and telson are more compressed 

 than in the type. 



2. The keels of the sixth abdominal segment are produced, without constriction 

 into long spines. 



3. The upper edge of the middle keel of the telson is almost straight, and is 

 produced backwards into a spine. 



4. The 'flukes' of the anchor on the telson are represented by two narrow ridges 

 running forwards from the hind end of the middle keel. 



5. On each side of the first five abdominal tergites is a small, sharply-defined, dark spot. 



Lastly, the Gonodactylus oerstedi of Hansen^ may be considered in connection with 

 the above forms, since it differs from them no more than they from one another, 

 and rests its claim to specific rank mainly on its geograiihical distribution. It is 

 characterised by the presence of a small swollen ridge on the inside of the keel of 

 the intermediate spine of the telson, and in other respects resembles the type variety 

 of G. chiragra. It is at present known only from the West Indies and east coast of 

 America. 



The distinguishing marks of the above forms may be set forth in key form as 

 follows : — 



1. Without a swollen ridge on the inside of the keel of the intermediate telson- 

 spine. Distribution Indopacific. 



2. Keels of sixth abdom. segment and telson rounded, not produced without 

 constriction into spines. Middle keel of telson without a spine. 



3. Middle keel of telson anchor-shaped. 



Variety A. (type). 



3'. Middle keel of telson not anchor-shaped. 



4. Outer angles of rostrum not acute. Keels of submedian telson-spines not con- 

 verging forwards. 



Variety B. {anancyrus). 



4'. Outer angles of rostrum acutely pointed. Keels of submedian telson-spines 

 converging forwai'ds. 



Variety C. (acutirostris). 



' P. Z. S., 1893, p. 34, where it is claimed that this form is but a variety of G. chiragra. 

 2 Plankton-exped., laop. Cum. u. Stem., p. 65. See also P. Z. S. loc. cit., PI. V., Fig. 3. 



