ON HEBRIDIAN INVERTEBRATA. 207 



examining its structiire, we find that this bulbous portion consists of two 

 cells, divided from each other by a thin wall of shell, and that the triangular 

 tube of the general body is continued through its base, with the mouth of the 

 tube opening generally immediately below it. In one instance, however, the 

 tube is continued for a short distance in front of the sweUidg. Mr. Jeffreys 

 suggests that this protuberance may be an egg- ease, which I think is very 

 probable, as there is a small external aperture in front of each partition, 

 which apparently communicate with the tubular portion posteriorly. I am 

 not aware that any similar structure has been before observed in the tabular 

 Annelids ; and I therefore now take the opportunity of bringing the circum- 

 stance under the notice of naturalists, in order that it may be investigated 

 by those more immediately connected with the study of this department of 

 zoology. The species appears to be a new one ; but it is impossible to speak 

 with certainty in the absence of the animal inhabitant of the tube. In one 

 individual two of these protuberances have been formed, one behind the other. 



Pennatfla mollis, n. sp. I 5^ 'l? .5 ■ ^ • * f " 2- 



Pohjpary 4 or 5 inches long, of a brick-red colour, variegated with darker 

 red streaks, slender, rather soft and flaccid. Stem slender, rovmded, smooth, 

 and very slightly bulbous at the base, occupying from one-third to half the 

 length of the compound body. Rhacliis smooth in front, except an undu- 

 lating line of tubercles running at the base of the pinnae on each side ; the 

 back of the rhachis has a smooth groove in the centre, on each side of which it 

 is set with small pointed granules, smaller and less crowded than ia P. plws- 

 fliorm. Pinnce compressed, flaccid, slightly fusiform, about half an inch long 

 in the centre of the rhachis, but decreasing towards each end ; these terminate 

 in a rather obtuse point at the apex, and diminish gradually to minute pro- 

 cesses below ; they are placed a Httle further apart, are less triangular, and 

 have a narrower base than those of P.pTiosjpliorea. Polype-cells cylindrical, set 

 in a single row on the front margin of each pinna, and terminating as usual 

 in eight denticles ; they are rather shorter and less spiculose than in P. phos- 

 pTiorea, and number about twelve in each row of the longer pinnee. This species 

 has considerable resemblance to the Pennatula phosphorea of our coast, the 

 difierences between them, though weU marked, being only comparative. It 

 is larger, more slender, and much softer and more flaccid in all its parts than 

 that species. This latter character arises principally from the fewer spicula 

 in its composition, from which cause also it is of a paler and duller red, the 

 colouring-matter being principally confined to the spicula. The pinnae are not 

 so crowded as in P. pliosphorea, and are less fii-mly and broadly set on the 

 rhachis, leaving a little more space in front. 



It is probable that this may be Pallas's Pennatula rubra, var. /3, of which 

 he says, " Datur varietas, in oceauo praesertim, longior, gracilior, pianis 

 angustioribus, magisque distantibus, caliculis pinnarum rarioribus et promi- 

 nentioribus." There can be little doubt, however, that this species is distinct 

 from the P. rubra of Pallas, which is the P. p>7iosp7iorea of British authors, and 

 probably also of Linne. The differences between them are as great as is 

 usual in other species of this genus. 



This is an interesting addition to our faiina, one species only of Pennatula 

 having been previously known as British, 



Ttjnicata. 



Ascidia mentula. I Ascidia plebeia. 

 venosa. | aspersa. 



