448 W. F. LANCHESTER. 



V. PL XXIII. fig. 5 with which it may be included, and which differs fi-om it only in 

 the definite presence of carinas proceeding from the base of the spine, and forming an ' anchor.' 



3 t/cT. length 29, 30-5. and 18, and 3 ??, 51-5, 36, and 27-5. Hulule, Male Atoll, 

 Maldives. From the reef. 



This is the type of var. smithii as figured by Pocock. 



VI. Var. segregatus a. var. nov. PI. XXIII. fig. 6. 



This variety is very similar to var. smithii, but has the carinae slightly more swollen, 

 with the spine not quite so prominent, and the flukes of the anchor separated from the base 

 of the spine, and forming two low carinae extending not more than halfway along the sides 

 of the median carina. 



4 $$, length 13, 12, 11, and 9, Goidu, Goifurfehendu Atoll. From the reef; 1 J", 9-5, 

 South Male Atoll, 25/.; 1 ?, 17, Minikoi, from the reef; 1 ?, 7-5, Hulule, Male Atoll, 

 from the reef; and 1?, 12, South Nilandu Atoll, 25/ 



It will be seen that the representatives, in this collection, of this variety are all of 

 comparatively small size, and the imperfection of the anchor might be due to this fact. But 

 I have also seen similar examples, in the collection of the Natural History Museum at 

 S. Kensington, from the Macclesfield Bank, eight in number, and ranging from 20 to 30 mm. 

 in length ; while some specimens from the ' Skeat ' collection of Crustacea, which differ only 

 in the absence of the spine on the median carina, but agree in the separation of the flukes 

 of the anchor, and to which I shall refer later, range from '20 to 28 mm. in length. 



VII. Var. segregatm b. PL XXIII. figs. 7 and 7 a. 



Some small specimens, quite similar to var. segregatus, but the separated flukes of the 

 anchor, or sometimes one only on one side, bear a small spine at their distal extremity; this 

 I should include under var. segregatus. 



1 ?, length 18-5, North Male Atoll, 27—35/; and V, 17-5, and 4 %%, 14-5, 13, 12, 

 and 7-5, South Nilandu Atoll, 19 / 



VIII. Var. glabrous Brooks. PL XXIII. figs. 8, 9 and 15. 



This includes the G. glabrous of Brooks and G. glaber of later authors, together with 

 some additional forms to which reference will be made below (p. 451). On this variety it 

 will be necessary to make some preliminary remarks before attempting any description of it, 

 and in these remarks I shall deal with the variety as a whole, although I have, from the 

 point of view of the transition scheme, separated off a portion of it under the second heading 

 as in the case of var. segregatus. Now in dealing with the specimens of this variety in 

 the collection I found that, though I could distinguish two extremes of structural form readily 

 enough, yet I could not separate the individuals into two groups corresponding with these 

 extremes, the intermediates between the two being relatively numerous and presenting all 

 grades of slight structural differentiation. And, in spite of the smallness of the number before 

 us, it seems to me legitimate to infer, from the evidence as it stands, that we have here 

 a case of a Continuous (or Normal) Variation ; and in fact that, different though the two 

 extremes are structurally, yet they cannot be considered as varieties in the strict sense of 

 the word, in face of the intermediates which exist between them. I must not, however, be 

 taken to underrate the danger of arguing from such a small number of specimens ; the facts 



