288 MB. F. P. BEDFORD ON MALAYAN ECHINODERMS. [Mar. 20, 



also at Singapore. The question of the extent to which the same 

 species alters as it migrates from its specific-centre is one the 

 solution of which must lead to a clearer idea of the mode of origin 

 of new species (or rather perhaps new " form-units "). In many 

 eases the same range of variation appears to occur throughout the 

 whole area of distribution of the species, while in other cases we 

 can speak of local varieties or local races ; and in such, attempts 

 have been made to trace a gradual progressive modification as we 

 pass outwards from the supposed original " centre." This has been 

 exemplified in some detail by Dr. Doderlein ' for two species of 

 Culcita. In this genus the form and distribution of the pore-areas 

 over the abactinal surface vary considerably within the limits of 

 the same species, and in the two species, C. schmideliana and 

 C. novce-guinecv, these pore-areas have a similar independent range 

 of variation from forms with small disconnected areolae to others 

 in which the areola? merge into one another, leaving small isolated 

 spaces devoid of pores. C. schmideliana var. ceylonica and C. novce- 

 guinece var. plana belong to the former type, while 0. schmideliana var. 

 africana and G. novce-guinecB var. arenosa belong to the latter type. 

 The distribution of the two species is as follows : C. schmideliana 

 occurs in the western part of the Indian Ocean, while C. nova- 

 guineas extends throughout the Malay Archipelago and Eastern 

 Pacific. Dr. Doderlein points out that at Ceylon var. ceylonica 

 occurs, while at Sumatra and Java, the most western points to which 

 C. nova-guinea; extends, var. plana is found; and from this he draws 

 the conclusion that " wo die Verbreitungsgrenze beider Arten 

 aneinanderstosst, finden sich Varietaten, die einander auffallend 

 ahneln." From this it would appear that the two species originated 

 from a form intermediate between var. ceylonica and var. plana, 

 and that the specific-centre of this form would lie between Ceylon 

 and Malaysia. This, however, is at once falsified by finding the 

 opposite extreme of variation, viz. var. arenosa, at Singapore, a point 

 nearer to Ceylon than the places at which var. plana has been 

 collected. This merely shows how important it is to determine the 

 distribution of varieties before questions of position of specific- 

 centre can be solved, and it will serve, I hope, as an apology for 

 what may be regarded as unnecessary detail in the descriptions 

 I have given of specimens collected. In the case of Astropecten 

 javanicus we appear to have a case of progressive modification as 

 we pass from Java through the Straits of Malacca to the Mergui 

 Archipelago, where A. andersoni, which I believe to be a variety of 

 A. javanicus, is found ; but it would be rash to assume this until the 

 region is more fully worked out. 



I have adopted in all cases the generic and specific notation 

 employed by Professor Ludwig 2 , as it seems to me preferable to 

 attempt to impress some uniform scheme into systematic reports 

 rather than to wage an incessaut war of words in defence of 

 doubtful claims to priority. 



1 Semon's Zool. Forsch. in Austr. &c. Bd. v. Lf. 3, 1896, pp. 310-316. 



2 Bronn's Thier-Beich, Bd. ii. Abth. 3, Asteroidea, 1899. 



