94 ZOOPHYTOLOGY. 



of the latter species I am indebted to Mr. Wyville Thomp- 

 son ; and from one of these, fig, 3, PI. VI., has been taken 

 for the purpose of comparison ; the two having been drawn 

 under the same magnifying power. It should be remarked, 

 however, that the specimen of the latter here figured was in 

 the dry state, and consequently is somewhat distorted. But 

 since these figures were printed I have met with a species 

 of Farrella, parasitic upon Fliistra foliacea, dredged in about 

 20 fathoms of water off Tenby, which appears to correspond 

 with the Avenella fusca, and the examination of which in the 

 living state has satisfied me beyond doubt, that that form and 

 Farrella qiqantea are quite distinct. In the ' Annals of Nat. 

 Hist.,' 2nd Ser., vol. xvi., p. 35, Plate IV., fig. 29, Mr. Gosse 

 describes and figures a Polyzoan belonging to the same 

 family, under the name of Nolella, which would appear 

 closely to approach in some respects, as he himself observes, 

 the Avenella of Sir J. Dalzell ; and from the semiopacity 

 assigned to the ectocyst, it would also seem to correspond 

 very closely with the form above adverted to, as found upon 

 Flustra foliacea. The characters, however, assigned by Mr. 

 Gosse to Nolella are apparently sufficient to remove all 

 suspicion of this being the case. He says, that the " cells 

 are erect, subcylindrical, springing singly, but closely from 

 an undefined polymorphous incrusting mat ; the tentacles (18) 

 forming a bell." A copy of Mr. Gosse's figure of N. stipata 

 is given in Plate V., fig. 4. 



What is meant precisely by the expression " undefined, 

 polymorphous incrusting mat," from which the cells spring, 

 is not very clear. In all known Vesiculariadan Polyzoa, 

 except Anguinella, the cells spring " singly " from a common 

 tube ; and if, as the use of the word " mat " might imply, the 

 " polymorphous crust " is composed of tubes, the character is 

 intelligible enough, and the species in accordance, so far, with 

 its congeners ; but if, as the expression might also be taken 

 to convey, and as the figure certainly indicates, this crust is a 

 continuous substance, — the condition is so peculiar as at once 

 to raise the genus in which it is found to the rank of, at 

 least, a distinct family gi'oup. It is more probable, however, 

 that upon farther examination Mr. Gosse will find that the 

 cells do really arise from a creeping adnate tube ; in which 

 case the genus will fall to the ground, and Nolella stipata have 

 to be referred to Farrella, with the characters as here modi- 

 fied. If so, it would seem to correspond in all respects with 

 Avenella fusca, Dalzell ; or, at any rate, with the form occur- 

 ring in Flustra foliacea above noticed, and which, if not the 

 Avenella, is apparently as yet undescribed. 



