1886.] MR. F. E. BEDDARD ON A LARGE EARTHWORM. 16!) 



drilu.1^. This genus is already known to inhabit New Caledonia; 

 M. Pcrrier has described two distinct species from that region. The 

 species which forms the subject of the present communication may- 

 be identical with one or other of these. The descriptions given by 

 M. Perrier oi Acanthodrilus ohtusus and^. angulatus are necessarily 

 insufficient, owing to the poor condition and immaturity of the 

 specimens at his disposal ; but certain facts, such as the position of 

 the generative apertures and of the clitellum, could hardly be 

 mistaken even in specimens greatly injured through bad preservation ; 

 in these points the present species differs from both of those de- 

 scribed by Perrier, as will be apparent from the following notes on 

 its structure. 



External Characters. — I have sketched (Plate XIX. fig. 1) the 

 anterior segments of the body from the dorsal aspect to indicate the 

 main external features which are visible upon that surface. The 

 buccal lobe divides the first segment ^, as also in A. disshnilis and 

 A. novce zelandice, two species recently described by myselt^. Of a 

 fourth species of the genus, viz. A. verticillatus, M. Perrier writes ^ :— 

 " La lobe cephalique n'entame pas le premier anneau et parait au 

 contraire s'elargir asabase demanierearesscmbleralapartiesuperieure 

 d'un trt'fie ; mais cette apparence tient peut-etre a un etat particuiier 

 de conservation." I mention these facts because the genus Lumbricus 

 has been split up into other genera mainly on this account. It does 

 not appear to me advisable, while there are so many internal structural 

 differences, to make use of so small an external character for 

 classificatory purposes ; but in the case of the genus Acanthodrilus 

 this mark of difference between species appears to be correlated with 

 other differences of structure, inasmuch as M. Perrier hesitates to 

 include A. verticillatus in the same genus with A, obtusus ; the 

 male generative pores in the former species are upon the 17th 

 and 18th segments and are not separated by an intercalated segment 

 as in the latter and all the other species of the genus at present 

 known. On either side of the buccal lobe, and consequently between 

 the first and second segments of the body, is a single pore ; these 

 may perhaps correspond to the single median dorsal pore which is 

 the only orifice of the kind found in the Oligochseta limicolae. 



The clitellum was fully developed in several specimens, and 

 extended from the 13th to the 17th segments inclusive, with the 

 exception of a portion of the 13th segment; the glandular tissue 

 composing the clitellum was only visible on the posterior half of that 

 segment ; the clitellum extends occasionally for a short distance on 

 to the 1 8th segment. The anterior region of the clitellum down to 

 the 15th segment completely encircles the body ; the 17th and 18th 

 segments, on the contrary, have a very considerable median area upon 

 which there is no glandular development ; the lateral margins of this 



' Perrier, "Eecherelies pour servir a I'histoii'e des Lombricieus terrestres," 

 Nouv. Arch. d. Museum, t. tiii. (1872) p. 85. 



^ 1 Lave reckoned tlie first seta-bearing segment as the second segment of the 

 body, in common with the mnjority of naturalists who have studied this group. 



^ P. Z.S. 1885, p. 813. " Loc. cit. p. 03. 



Proc. Zool. S0C.--I886, No. XII. 12 



