. The Cambridge natural history. Zoology. 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 ^ and ^ in Fig. 14 being stated to be really continuous with one another, while the " subneural sinus " () is regarded as a part of this Fi
. The Cambridge natural history. Zoology. 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 ^ and ^ in Fig. 14 being stated to be really continuous with one another, while the " subneural sinus " () is regarded as a part of this Fig. 14.—Actmoiroclxa-\!X!%'a, of Phoronis. a, Anus; ^, ^, \ first, .second and tliird body-cavities ; c, circular nerve, running in tiie posterior boundary of tbe collar, immediately beliind the ring of ten- tacles ; , ciliated ring ; (7, diverticulum (paired) of alimentary canal; m. nioutli; , central nervous system ; p, nerve running round the ventral border of tbe proboscis; s, sense-organ; 6'.5, subneural sinus, a vascular space whose hind wall is con- stituted by the front boundary of &.c^, its front wall being formed by the hind wall of ^ ; in this region is seen a median outgrowth of the alimentary canal, which may be compared with the notochord of Cephalodisms, or of the young Tornaria (cf. Morgan, J. Morjjhol. v. 1891, Plate xxvi. Fig. 40.) (After Mastermau.) 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 ^ -I- most of ^ 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.
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
