164 REPORT — 1851. 



Gasteropods should rank somewhere between the Chiton and Patella. In 

 Dentaliiim, the symmetrical subventral position of the branchiae, the posterior 

 flow into them of tlie water, and the resemblance of the foot to that of some 

 of the bivalves, appear in a striking manner to prove its connection with the 

 Conchiferae; whilst by its oesophageal cerebral ganglions, and the completeness 

 of its circulating system, its affinity to the Gasteropod is established. But it 

 cannot be disputed that there are, on the other hand, evidences of approxima- 

 tion to the Annulose tribes ; the red blood, and the vermiform configuration 

 of the posterior part of the body, the tubular figure of the shell, the operation 

 of the operculum, the apparent resemblance of the branchiae to those of the 

 Sabellce, may be readily conceived as prefiguring some of the outward features 

 of the Annelida. These points of analogy however are merely apparent and 

 supel-ficial ; the Dentaliadce are therefore hereby excluded from the pale of 

 this Report. 



Both Cuvier and Lamarck saw in the Cyclostomatous fishes indications of 

 resemblance to the Annulose tribes. In the anatomy of Amphioacus there 

 exists only one fact of structure which likens it to the Annelid. The circu- 

 lating system consists of two longitudinal trunks, a dorsal and ventral; the 

 movement of the blood, however, being the exact reverse of that of the An- 

 nelids ; the current in the dorsal vessels sets in the direction of the tail, that 

 in the ventral forwards I The affinities of the Amphioxus, indeed, connect it 

 much more intimately with the Ascidian MoUusk than with the Annelid. 



The data to be advanced in the subsequent portions of this Report will 

 prove that a much closer analogy exists between the Annelida and the Ento- 

 zoa than that which is implied in the received divisions of systematic natu- 

 ralists. It will be shown that in every detail of organization the Cestoid En- 

 tozoa link directly with the genera Borlasia and Lineus, both of which rank in 

 the family of the Planarice, The disposition of the intestine, the peculiar situ- 

 ation of the chylo-aqueous fluid, the curving of the intestine as in the Sipuncu- 

 lidcB, the corpuscles of the chylo-aqueous fluid in these latter marine worms, 

 establish between them and Tcenia an immediate relationship. But the au- 

 thor has proved that in the PlanaricR the csecal ramifications of the digestive 

 system are not, as taught by Owen and all other comparative anatomists, 

 adherent to the parenchyma of the body ; for a fluid, rendered visible by 

 moving corpuscles, intervenes and is set in motion as in the Echinoderms by 

 vibratile cilia. This fluid, of which much more will hereafter be stated, 

 exists also in the Cestoid Entozoa, and suggests doubts as to the propriety of 

 the nomenclature of Prof. Owen, in which they are characterized as solid- 

 worms, or Sterelmintha. 



In the Nematoid Entozoa, the space between the intestine and integument 



is more capacious and filled with a much larger amount of that fluid, which 



in this Report it is proposed to distinguish under the name of Chylo-aqtieoics 



fluid. This division of the Entozoa is denominated by Professor Owen the 



Coelelmintha or cavitary worms. 



Notwithstanding the recent excellent researches of M. Blanchard*, the 

 difficulties raised by the investigations of the author of this Report on the 

 structure of the allied genera of Annelida, will demand a re-examination of the 

 whole class of Entozoa. Impressed at present in a strong manner with the 

 conception of the essential unity of the type on which the Entozoa and Anne- 

 lida are constructed, we applaud the caution and doubt with which Professor 

 Owenf speaks as to the place in the zoological series in which the Entozoa are 

 made at present to stand. " These animals are associated together chiefly in 

 consequence of a similarity of local habitation, which are the internal parts 



* Ann. des Sci. Nat. 1849. f See Art. Entozoa, Cyclop. Anat. and Physiology. 



