Valkeuia. ZOOPHYTA. SERTULARIADJE. 551 



ria cus. Linn. Syst. i. 1311. Pall. El. 125. Abild. ZooL Dan. t. cxvii. 



f. 1, 2, 3 Valkeria cus, Flem. Wern. Mem. iv. 485. t. xv. f. 1 On 



Corallines in deep water. 

 Height seldom above two inches ; several stems usually arise from the 

 same base, filiform, jointed, waved, and support the branches and cells bifa- 

 riously ; branches opposite, nearly perpendicular to the stem, with a joint 

 immediately above their insertion; cells oval, sessile, upwards of 10 times 

 the breadth of the stem, in pairs, at remote distances, projecting, and are 

 probably ultimately converted into branches ; sometimes they occur in pairs 

 or crowds in the axillae of the branches ; polypi extend considerably beyond 

 the margin, tentacula with hairs, which, by their motions, cause the water to 

 ascend in a current on one side, and descend on the other, acting, probably, 

 as aerating organs. 



197. V. Uva. — Stem creeping, irregularly branched, cells 

 scattered. 



Grape coralline, Ellis, Cor. 27, t. xv. f. 25. D. — Sertularia uva, Linn. 

 Syst. i. 1311. — S. acinacea. Pall. El. 123. — Clytia uva, Lamour. Cot. 



Flex. 203 On Flustra foliosa. 



Stem creeping, much waved, cells oval. This is a species, the true cha- 

 racters of which are involved in considerable obscurity. 



* Stem compound. 



198. V. spinom. — Stem erect, dichotomously divided, waved ; 

 cells on one side. 



Silk coralline, Ellis, Cor. 20. t. xi. f. 17- B — Sertularia spin. Linn. Syst. 



i. 1312 S. sericea. Pall. El. 114 — Laomedia spin. Lamour. Cor. Flex. 



208 On oyster beds. 



Height upwards of a foot ; slender, like silk ; principal stem formed by 

 the union of several tubes, dichotomously divided ; subordinate branches al- 

 ternate, and dichotomously divided ; the cells seem confined to one side, ra- 

 ther distant, oval, sessile. 



Gen. LXXI. CYMODOCIA.— Stem tubular, annulated 

 below, united above, without any internal partitions ; cells 

 cylindrical, filiform, alternate or opposite. 



199. C. comata. Stem erect, branches verticillate and 



Avaved. 



Lammir. Zoopli. 15, t. Ixvii. f. 12, 13 — Coast of Devon, Dr Leach. 

 Stem straight, cylindrical, slightly divided ; branches capillary, jointed, a 

 minute cell at each joint, with a wrinkled base. Structure yet obscure. 



At the close of this group of animals may be noticed the doubtful Serlula. 

 ria pustulosa of Ellis, Cor. 57, t. xxvii. f. B. It is described as jointed, and 

 alternately but thinly branched ; towards the upper part of every joint are 

 several shallow cells, having a little circular rim with a point in the middle 

 of each. Its relations remain to be determined. 



