I PHORONIS AND ACTINOTROCHA 29 
recently been published by Ikeda,’ de Selys Longchamps,? Good- 
rich,’ and Schultz,* who criticise many of Masterman’s  state- 
ments. While it is admitted on all sides that an oblique septum 
following the line of the bases of the tentacles completely sub- 
divides the body-cavity, Masterman’s account of the anterior 
cavities is not confirmed, the spaces indicated by 0.c' and b.c? in 
Fig. 14 being stated to be really continuous with one another, 
while the “subneural sinus” (s.s) is regarded as a part of this 
Fic. 14.—Actinotrocha-larva of Phoronis. a, Anus; 
b.cl, b.c?, b.c?, first, second and third body-cavities ; 
c, circular nerve, running in the posterior boundary 
of the collar, immediately behind the ring of ten- 
tacles ; c.r, ciliated ring ; @, diverticulum (paired) of 
alimentary canal; #. mouth; .s, central nervous 
system ; p, nerve running round the ventral border 
of the proboscis; s, sense-organ; s.s, subneural 
sinus, a vascular space whose hind wall is con- 
stituted by the front boundary of 6.c?, its front 
wall being formed by the hind wall of 6.c!; in this 
region is seen a median outgrowth of the alimentary 
canal, which may be compared with the notochord 
of Cephalodiscus, or of the young Tornaria (ef. 
Morgan, J. Morphol. v. 1891, Plate xxvi. Fig. 40.) 
(After Masterman.) 
space. It appears, however, from the account given by Ikeda, 
and followed by Goodrich, that the old Actinotrocha has two 
distinct spaces in front of the septum. The first of these corre- 
sponds with b.c’ + most of bc? in Fig. 14, and is continuous 
with the cavities of the larval tentacles. Into it project the 
blind ends of the larval excretory organs, which, according to 
Goodrich, bear numerous “ solenocytes ” similar to those described 
by the same author in Amphioxus and in Polychaet worms (Fig. 
79, p. 127). The second cavity is a relatively small crescent 
(not shown in Fig. 14), lying on the anterior face of the septum, 
1 J. Coll. Japan, xiii. Pt. iv. 1901, p. 507. 
2 Arch. Biol. xviii. 1902, p. 495; Wiss. Meeresuntersuch. vi. Abt. Helgoland, 
Heft 1, 1903. 
3 Quart. J. Micr. Sci. xlvii. Pt. i, 1903, p. 103. 
+ Zeitschr. wiss. Zool, \xxy. 1903, pp. 391, 473. 
