Rev. T. Hincks on new British Hydroids. 45 



a pale dull yellow colour ; an obscure line of the same hue ex- 

 tends from each of the latter nearly to the spinners, where the 

 two meet, and between the former a reddish-brown protuberance 

 is situated. 



VIII. — On some new British Hydroids. 

 By the Rev. Thomas Hincks, B.A. 



[Plate IX. vol. X. figs. 3, 4.] 



Fam. Tubulariadae. 



Genus Atractylis, Strethill Wright. 



A. margarica, n. sp, PI. IX. fig. 4. 



Polypary a network of delicate anastomosing tubes, from 

 which rise at intervals small chitinous cups, somewhat funnel- 

 shaped, which invest the base of the polypes and of the gono- 

 phores. Polypes white, scattered, slightly retractile ; the body 

 elongate, expanding towards the upper extremity, which is 

 encircled by a verticil of about twenty-four muricate tentacles, 

 alternately erect and depressed. Half of them are furnished 

 near the base with a prominent cluster of large bean-shaped 

 thread-cells, which projects outwards as a pearly boss or tubercle. 

 This gem-like setting round the tentacular ring gives a very 

 beautiful and distinctive appearance to the species. Gnnophores 

 produced on the creeping stem, close to a polype, either singly 

 or in pairs, of large size, pedunculate, the pedicle tapering to- 

 wards the point of attachment, and sheathed at the base in a 

 chitinous tube, sub-globular, crowned by a kind of lid (PI. IX. 

 fig. 4 h), which seems to be cast ofi" as development proceeds. 

 From the bottom of the sporosac, which occupies the whole 

 interior of the gonophore, rise four branched processes, of an 

 orange-colour (representatives of the gistrovascular canals), 

 which, as it were, embrace the ova. The latter are produced in 

 great numbers (300 in a single gonophore), and exhibit a very 

 distinct vesicle and spot. 



Habitat. Ilfracombe ; abundant on Flustra foliacea, and on 

 this only, from about 10 fathoms. 



In this very singular and_ beautiful species, the character 

 which at once attracts attention is the series of projecting bosses 

 round the base of the tentacular ring. When examined with 

 the microscope, these are seen to consist of a number of elongate 

 beau-shaped thread-cells (fig. 43-), which are piled together so 

 as to form silvery-white prominences on the lower side of the 

 tentacles. They occur, I believe, only on the alternate arms, 

 and constitute a unique garniture. 



