88 



polypary ; stems erect, funnel-shaped, developed at intervals 

 on a creeping stolon ; polypites emerging from the summits 

 of the stems, into which they are retractile, fusiform, with a 

 conical proboscis , surrounded by a single verticil of filiform 

 tentacula. Reproduction by fixed sporosacs, which are 

 invested by a chitinous envelope and borne on the sides of 

 the stem. 



ATRACTTLIS is distinguished from Perigonimus solely by 

 its mode of reproduction. A simple fixed sac takes the 

 place in this genus of the medusiform zooid. The ovary 

 contains a very large number of eggs, developed as usual 

 between its two component layers ; and these at a certain 

 stage are forced, after " a most laborious process of partu- 

 rition"*, through the ruptured wall of the sac into a kind 

 of gelatinous nest which crowns it (Plate XVI. fig. 1 b}. 

 There they are matured into planules. This extracapsular 

 nidus is not uncommon in the next suborder (Thecaphora] . 

 Sertularia pumila and Calycella syringa offer examples of it. 



A. ARENOSA, Alder. 



ATRACTYLIS ARENOSA, Alder, Supp. North. Cat. in Trans. Tynes. F. C. v. 231, 

 pi. ix. figs. 5-7 ; T. S. Wright, Micr. Journ. (N. S.) iii. 47, 

 pi. iv. figs. 7-10. 



Plate XVI. fig. 1. 



STEMS short, funnel-shaped, generally covered with minute 

 grains of sand or with mud; POLYPITES milk-white, with 

 long, slender tentacles alternately elevated and depressed, 

 6-12 in number, according to age; GONOPHOBES pyriform, 

 shortly stalked, borne on the lower half of the stem, 

 usually two in number, one opposite to the other. 



THE stems of this species, though somewhat irregular in 



* Vide " Observations on Brit. Zoophytes; 1 by Dr. T. Strethill Wright, 

 Microscop. Journ. vol. iii. (N. S.). 



