258 SERTULARIIDJS. 



7. D. ALATA, Hincks. 



" Notes oa British Zoophytes," Ann. & Mag. N. H. for February 1855,(ser.2) 

 xv. 127, pi. ii. 



Plate XLVIII. fig. 2. 



ZOOPHYTE blackish brown, highly varnished; STEM straight, 

 rather thick, pinnate; pinnae alternate, approximate, 

 long, not constricted below the calycles, keeled along one 

 side, and attenuated towards the base; HYDROTHEC.E 

 elongate, adherent for about two-thirds of their length, 

 the upper part suddenly divergent, wide, rounded below, 

 concave above, aperture oblong, the outer margin everted ; 

 GONOTHEC.E (male) very small, tapering towards the 

 base, subquaclraugular above, with a mucro, which bends 

 inwards at each corner; (female) unknown. 



Height from 3 to 5 inches. 



THIS species is closely allied to the Sertularia mutulata, 

 a native of Torres Straits, described by Busk in 'The 

 Voyage of the Rattlesnake/ The only form of gonotheca 

 hitherto found on it is characteristic of the male sex 

 throughout this genus. The hydrothecse are minute ; the 

 free portion is abruptly divergent, and stands out like a 

 bracket from the stem. 



The shoots of D. alata are regularly pinnate, and the 

 pinnae are almost always simple. They are not constricted 

 below each pair of calycles, as in most of the other mem- 

 bers of the genus, but of uniform thickness through a 

 great portion of their length, becoming slightly attenuated 

 towards the base. A prominent keel runs down the centre 

 of each pinna on one of its aspects and of the main stem. 

 The colour of D. alata when dried is very dark, and the 

 surface highly polished. 



Hab. Shetland (Barlee) : one mile north of Whalsey 

 Lighthouse, Shetland, in 40 fathoms, rare; Hebrides 

 (A. M. N.): Falmouth (Cocks): Cornish coast (C. W. P.). 



