DR. W. B. CARPENTER ON TOMOPTERIS ONISCIFORMIS. 361 



of the body are bifid, and in large specimens the lobes of the posterior not-fully-developed 

 appendages are relatively larger than the former. One of the most important parts 

 of Grube's memoir relates to the nervous system. He asserts that he has distinctly seen, 

 in many specimens, a double nervous cord passing backwards along the ventral surface of 

 the body from an cEsophageal ring, of which the upper part is formed by the cephalic 

 ganglia. This double cord, he says, does not anjTvhere present ganglionic enlargements ; 

 but, when examined under a high magnifying power, it presents a series of transverse 

 striae at short intervals. I cannot but express some doubt as to the existence of this 

 ventral cord; for Grube's description of it is entirely based upon preserved specimens*; 

 and although I looked for it carefully and repeatedly in living specimens, I was not able 

 to detect it. Grube's description of the muscular structure also, especially in the fins, is 

 very minute ; but I can state confidently that this presents itself \mder a very different 

 aspect dm-ing life ; indeed, as to the general histology of the creatm-e, I was struck Avith 

 the remarkable change which it seemed to undergo when the animal appeared to be 

 suffering from confinement, but while as yet far from having lost its vital activity. 



The most recent notice of Tomopteris is that given of it by Mr. Gosse in his ' Natu- 

 ralist's Rambles on the Devonshire Coast ' (p. 356), under the name of Johnstonella 

 Catharina ; it adds nothing, however, to what had been previously recorded, excepting as 

 to the occasional eversion of the pharynx so as to form a protruded proboscis, which 

 Mr. Gosse seems to have been the first to observe. His specimens appear to have been 

 in the same stage of development as my most advanced specimen, having 16 pairs of 

 fin-like appendages, and a caudal prolongation without any obvious appendage. He 

 seems to have overlooked the posterior paii- of frontal "horns," which, for the reason I 

 have stated, are not to be seen in the larger specimens unless carefully looked for. In 

 his ' Marine Zoology ' (vol. i. p. 106), Mr. Gosse has introduced Tomopteris (by its proper 

 designation) amongst the " animals of doubtful position, probably belonging to the Anne- 

 lida ;" and he has given a figure of it, which, Hke the figure in his 'Devonshire Coast,' 

 wants the second pau- of frontal " horns," and which is further eri'oneous as giATng not 

 the least indication of the bifid character of the fin-like appendages. 



There cannot, I think, be any longer a reasonable doubt as to the Annelidan character 

 of Tomopteris ; and the principal point which now requires Investigation seems to me to 

 be the question of the real natiu'e of the caudal prolongation, — that is, whether it is 

 simply an extension of the body, or is a zooid destined to be cast off and to maintain an 

 independent existence. The former view seems to be that of all pre\ious observers ; no 

 such marked peculiarity having been observed by them, either in the conformation of its 

 appendages, or in the structure of its integument and of the portion of the alimentaiy 

 canal included in it, as that which seemed to me to differentiate it completely from the 

 anterior part of the body, and to bring it nearer to the ordinary Annelidan type. I speak 

 with difiidence, however, on these points, since I find myself at issue in regard to them 



* It would be interesting to know in what fluid these specimens were mounted ; as I tried all the ordinary media 

 without succeeding iu preserving iu any specimens an approach to their life-like appearance. 



VOL. XXII. 3 E 



