120 FLU STRIDE. 



the mere outliue is traceable through the membranous 

 covering. The aperture of the ovicell is closed in by a 

 delicate membrane ; and at the top of it there is frequently 

 an opening of definite form, which probably gives egress 

 to the mature embryo. 



Flustra securifrons, Pallas. 



Plate XVI. figs. 3, 3 a. 



" Narrow- LEAVED Hornwrack," Ellis, Corall. 69, no. 1, pi. xxviii. fig. 1, a, 



A,B. 

 Eschara foliacea j8, Linn. Syst. ed. 10, 804. 

 EsciiARA SECURIFRONS, Palltts, Elench. (1766), 56. 

 FlustrjV truncata, Li7i7i. Syst. ed. 12, 1300 : Larnk. An. s. Yert. ed. 2, ii. 



219 : Flem. B. An. 535 : Johnst. Br. Zooph. ed. 2, 344, 



pi. Ixii. figs. 3, 4: Bu&k, B.M. Cat. i. 48, pi. Iviii. figs. 1, 2, 



and pi. Ivi. figs. 1, 2. 

 Flustra papyracea, BalijeU, Rem. An. ii. 19, pis. v., vi., and vii. (var.). 

 Chartella SEC0RIFRONS, Gray, Cat. Rad. B. M. 104. 

 Flustra securifrons, Smitt, Krit. Forteckn., ffifv. K. Vet. Ak. Fcirh. 1867, 



358 and 378, pi. xx. figs. 6-8. 



Zoarium bright straw-coloured, divided and subdivided 

 into narrow segments^ which are linear or slightly 

 dilated above, and truncate, rooted by many tubular 

 fibres. Zocecia linear, oblong, with unarmed margins. 

 Aviculai'ia scattered, elliptical, with a rounded man- 

 dible. Ooecia globose, with a slightly thickened rim 

 in front, the lower part of the aperture closed in by two 

 rib-like processes. 



Height 4 or 5 inches. 



Habitat. On shells, &c. from the Laminarian region 

 and the Coralline ground. 



Localities. Chiefly a northern form. Shetland (A. 

 M. N.) : Scotland, common (Johnst.) : Peterhead, abun- 

 dant (C. W. P.) : St. Andrews, Laminarian and Coralline 

 zones, common (Dr. M'Intosh) : Leith; Dirletou, opposite 



