90 ATBACTYLIDJE. 



The operculum is a very favourite site for the Periyo- 

 mmMS-settlement, affording no doubt peculiar facilities for 

 procuring an abundant supply of food. The alliance is far 

 from uncommon between the stationary zoophyte and 

 the mollusk or the restless Hermit Crab, the former securing 

 the advantages without the toils of a vagrant life, and 

 sharing the spoil without the fatigues of the chase. 



1. P. REPENS, T. S. Wright. 



EUDENURIUM PUSILLUM, Wright, Proc. Koy. Phys. Soc. Edinb. 1857, p. 231, 



pi. ii. figs. 8, 9; Ed. N. P. Journ. (N. S.) vi. pi. ii. figs. 8, 9. 

 ATRACTYLIS REPENS, Wright, Proc. Koy. Phys. Soc. Edinb. 1858, p. 450, pi. xsii. 



figs. 4, 5; Ed. N. P. Journ. (N. S.) ix. (1859,) 108, pi. i. 



figs. 4,5; Alder, Supp. Nortb. Cat. in Trans. Tynes. F. C.v. 230. 

 PERIGONIMUS REPENS and vvsiLixs,Allman, Ann. N. H. for May 1864. 

 PERIGOMMUS MINUTUS, All-man, Notes on Hydroida, Ann. N. H. for January 



1863. 



Plate XVI. fig. 2. 



STEMS erect, simple or bifurcate, more or less dilated and 

 cup-shaped above, from g to \ inch in height; POLYP IT E 

 small, club-shaped, white, partially retractile into the 

 upper part of the tube ; tentacles from 4-1 2, according 

 to age; GONOPHORES pedicellate, borne on the stems at 

 various heights. 



GONOZOOID. UMBRELLA mitre-shaped, with numerous 

 thread-cells in its substance ; MANUBRIUM 4-lipped ; 

 MARGINAL TENTACLES, at the time of liberation, 4, 

 springing from yellowish-brown bulbous bases at the 

 termination of the radiating canals two very long, two 

 rudimentary*. 



DR. WRIGHT first described this species under the name 

 of Endendrium pusillum. In a subsequent paper he trans- 

 ferred it to the genus Atractylis, and changed the specific 

 name to repens. As such it is quoted in his own writings 



* The latter seem to be sometimes undeveloped at the time of liberation, 

 but they soon make their appearance. 



