458 PEOF. A. DENDT OK SOME POIITTS IN 



A general description of the external form and internal struc- 

 ture of Caudina coriacea bas been given by me in my paper on 

 tbe Holotburians of New Zealand already referred to, while a 

 much more detailed account of the anatomy and histology of the 

 closely allied C. arenata has recently been published by Grerould *, 

 so that it is unnecessary to describe the general anatomy in this 

 place. As Caudina is still a comparatively little-known genus, 

 however, I may be allowed to remind the reader that the body 

 has a very peculiar form, consisting of an inflated, ovoid, anterior 

 portion, bearing the mouth and tentacles in front, and a narrow, 

 cylindrical, posterior portion, sometimes known as the "tail," 

 with the anus situated at its extremity. Eig. 13, PI. 29, though 

 taken from a young and consequently very small specimen, 

 exhibits the characteristic form of the species. 



The extreme tip of the tail of a very young specimen, dredged 

 in Lyttelton Harbour, exhibited the appearance shown in fig. 1. 

 It will be seen from this that tbe anus {a) is surrounded by 

 five somewhat triangular groups of papillae, which I shall pre- 

 sently show to be radial in position. Each group consists of one 

 larger projection, placed next to the anus and forming the apex 

 of the triangle, and (usually) seven smaller papillge, of which one 

 is placed exactly in front of the larger projection, while the 

 others are arranged in two diverging rows of three each on either 

 side, the most anteriorly placed being the smallest. The five 

 larger projections may have been those to which Theel referred as' 

 perhaps representing anal teeth ; and I shall show later on that 

 they are indeed quite difterent in structure from the others, 

 and that they are apparently present only in very young indi- 

 viduals. As Theel observed, these five larger projections contain 

 a specially well-developed skeleton, consisting of densely packed 

 irregularly branched spicules. As development goes on, however, 

 they seem to disappear completely, while the other papillae may 

 even increase in number, for in one adult specimen I counted as 

 many as nine of them in a group. Figure 2 represents a group 

 of these finger-shaped papillae, which I propose in future to 

 speak of as anal tentacles, from a specimen still quite small, 

 though apparently older than that from which fig. 1 is taken. 

 There are only six tentacles in this group, one of the most 



* Loc. cif. 



