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tinue anteriorly or posteriorly beyond the sole. Outside the sole 
the whole body is closely covered with small whitish tubefeet, 
which give the otherwise black body a finely spotted appearance. 
Even at the anterior and posterior end no serial arrangement of 
these tubefeet is discernible. No anal teeth. 
Tentacles 10, black, subequal. Calcareous ring simple, well 
developed (Fig. 43.d.) Retractor muscles short, attached in the 
iaterradial of calcareous ring. a—c. ; d. ^/i. 
anterior part of the body. One Polian vesicle and one very short 
stone canal. Oesophagus without muscular thickening. Genital coeca 
numerous, very long, unbranched, filling up the body cavity. Re- 
spiratory trees well developed. 
Calcareous deposits small, somewhat irregular, smooth plates, 
which lie in a close layer in the ventral sole, but hardly overlap¬ 
ping (Fig. 43.a.). Among these are found some finer, more regular, 
button-like plates, together with various developmental stages of the 
former sort. In the dorsal skin only the first sort of calcareous 
bodies occur, much more sparingly and accordingly not at all 
overlapping 5 they are slightly smaller than those of the ventral sole. 
