157 



size of the anchors and anchor-plates varies from less than 100 fi 

 to more than 350 but the usual size is ca. 250 /n. The anchors 

 and anchor-plates are in the posterior end of body often a little 

 larger and somewhat differing in shape from those more anteriorly. 

 In some species e. g. alba there are two distinctly different sizes 

 of anchors and anchor-plates all over the body, and in many species, 

 if not in all, there are some few very small anchors and anchor- 

 plates (these small anchors are often wanting and the anchor-plates 

 are found alone). These minute anchors and plates may (cf. the 

 description of hydriformis pag. 185) be the first post-larval or post- 

 embryonal plates. Malformations of anchors and plates are very 

 rare, except in neirensis (Fig. 22. 14 & 16). Malformed plates 

 are found in the specimens of recta and in a single specimen of 

 virgata. 



The miliary granules are, when present, usually (always?) ro- 

 settes. They are with certainty known to be wanting only in one 

 species, aspera. In some species e. g. psara, neirensis and madre- 

 porica, there are no rosettes, but circles of "minute granules". 

 Whether these "circles" are really characteristic of the named 

 species, or they are but the result of a partly dissolution of the 

 rosettes, it is not possible to see in preserved specimens. That 

 they may be due to dissolution is certain, for though three years 

 old balsam-preparations of rosea show distinct rosettes (Fig. 15. 16), 

 the miliary granules in the specimen from which the preparations 

 were made, are now three years after the nicest "circles" (Fig. 

 15, 13). The shape of the miliary granules is usually very charac- 

 teristic of the species and for this reason they often afford an 

 excellent systematical character. 



All the known species of Synaptula are littoral forms, and none 

 are known to occur in deeper water than ca. 100 m. When in 

 spite of this Herouard refers some fragments of Synaptids from 

 depths of ca. 2000 m in the Atlantic Ocean, to this genus, and 

 moreover to hydriformis, one of the most pronounced littoral species 

 (Holothuries provenant des Yachts Princesse Alice etc. 1923) we may 

 safely say that this identification must be erroneous (cf. Th. M or- 

 ten sen: Handbook of the Echinoderms of the British Isles, pag. 

 425, Note). 



In zoogeographical respect this genus is interesting in hydri- 



