15 



positively on the subject, he is inclined to regard them as being glandular in nature. The cirri 

 of L. cirriferum appear to be of the same nature as the "flash organs" ; but I think that 

 they are tactile organs, which are probably of special use in enabling the Loxosoma to avoid 

 injury by the formidable avicularia of the Retepore. 



Cirriform organs have been described in certain other species of Loxosoma. The structures 

 shown at the margin of the calyx in L. karmeri by Schultz a ) are probably of this nature. 

 More or less similar organs have been described by Assheton 2 ) in L. loxalimim and L. 

 saltans. The two "posterior sense-organs" of which I have given an account 3 ) in L. crassi- 

 cauda Sal. are perhaps more specialised organs of the same general nature; while more or 

 less similar structures have been described by Vogt '*) in L. phascolosomatum, by Nnxs 5 ) in 

 L. brumpti and by Mortensen °) in L. antedonis. But these species are all sufhciently different 

 in other respects from L. cirriferum to make it impossible to refer the 'Siboga' specimens to 

 any of them. 



Young individuals of L. cirriferum, whether advanced buds or recently detached free 

 forms, show no tracé of the cirri, which appear to increase in number as the individual grows 

 larger. Thus the small male specimen shown in hg. 1 3 has only two pairs of cirri. The small 

 specimens also differ from the large ones in another important particular, since they appear to 

 have a smaller number of tentacles. As in many other cases, in this genus, I have found it 

 difhcult or impossible to count the tentacles certainly. I have found evidence, however, that 

 the full number of the tentacles is 18, although other specimens, smaller in size, seem to have 

 no more than 16 or 14; or perhaps in some cases 12. It thus appears that, in the present 

 species at least, there is a progressive increase in the number of cirri and tentacles after the 

 individual has become free. 



L. cirriferum differs from the species next to be described in the fact that the females, 

 or the older ones at least, carry a number of embryos simultaneously in their vestibule. Cor- 

 related with this fact is the occurrence of a short row of eggs (about 3) in the ovary (figs 11, 12); 

 other species frequently having only one recognisable egg at a time in each ovary. Male spe- 

 cimens are usually smaller than females, although I have found a male almost as large as the 

 largest females. I find no evidence of protandry ; and eggs may be produced by females which 

 are no larger than the male shown in fig. 13. 



The buds in this species occupy a relatively proximal position. In the smaller indivi- 

 duals they are developed opposite what may be considered the middle of the stomach ; but 

 this organ has a considerable extension on the lophophoral side of the insertion of the buds, 

 which are thus situated nearer the proximal end than the distal end of the stomach (fig. 13). 

 In old individuals (fig. 1 2) the proximal insertion of the buds is very marked. It will be 

 obvious from the figures that buds are borne indifferently by males and females. 



1) Schultz, E., 1895, Trudui St Peterb. Obschch., XXV, Sect. de Zool. & Physiol. Pt II, text-fïg. on p. 51. 



2) Assheton, R., 1912, Quart. J. Mier. Sci., LVIII, pp. 118, 124, PI. VI, figs 1, 19. 



3) Harmer, S. F., 1885, Quart. J. Mier. Sci., XXV, p. 273, PI. XIX, fig. 1. 



4) Vogt, C, 1876, Arch. Zool. Exp. V, p. 312. PI. XI, fig. 3, PI. XII, fig. 1. 



5) NlLUS, G., 1909, Trudui St Peterb. Obschch., XL, Livr. 1, N° 4, e. r. séances, p. 16S, text-fig. on p. 165. 



6) Mortensen. Th., 191 i, "Danmark-Exsped. GrOnlands Nordostkyst", V, N° 8, p. 400, PI. XXVI, figs 2—4, 0. 



IS 



