168 REPORT — 1851. 



The names of Moquin-Tonquin of Montpellier and M. Phil'ippi of Milan*, 

 should be honoui-ably associated with this branch of comparative anatomy. 

 Hunter had formed a correct appreciation of the general structure of several 

 species of Annelids, as exemplified in the beautiful preparations which he has 

 bequeathed to the science, in the Hunterian collection f. The organization 

 of the Serpulce, the Amphitritce, and Nereidce, have been meritoriously studied 

 by M. Delle ChiajeJ. 



The researches of the earlier English zoologists were for the most part 

 limited to the descriptive history of species ; the names of Leach and Mon- 

 tague should, notwithstanding, be gratefully allied with this department of 

 natural science in England. Dr. George Johnston of Berwick-on-Tweed 

 has done more than any other modern observer to rescue the Annelids from 

 the region of obscurity and confusion. The descriptions of this excellent 

 naturalist are characterized by exactness and truth, and his investigations of 

 structure, as far as they have extended, seldom deviate much from the results 

 attained through aid of the modern microscope §. 



It is scarcely required to remark, that the efforts of ancient anatomists, how- 

 ever laborious, in those fields especially in which the subjects of investigation 

 were minute in size and of difficult manipulation, anterior to the era of the 

 microscope, could at best have been but imperfect. In the preparation of 

 this memoir, it will be accordingly found that the author will have few ac- 

 knowledgements to render to the works of these venerable authors. This 

 observation, however, does not apply to the labours of Owen and Milne-Ed- 

 wards, by whom, indeed, almost everything hitherto known to science with 

 reference to the organization of the Entozoa and Annelida has been contri- 

 buted. The researches of Milne-Edwards have been principally confined to 

 the system of the circulation in the Annelida|| ; those of Prof. Owen are re- 

 stricted to the Entozoa^. The author of this Report desires in this place to 

 bear testimony to the accuracy of the observations of Milne-Edwards. His 

 account, however, as stated, embraces little more than the central apparatus of 

 the circulation, and yet it will be subsequently seen that the study of the cha- 

 racters oi the periphery of the circulation, identified as it must be with the 

 intimate structure of the integral organs of the body, will conduct to results 

 of the highest interest. The author regrets that it has not been in his power 

 to refer in any satisfactory manner to the recent works of the Swedish and 

 Danish naturalists on the subject of the AnneMda. The reports by Prof. 

 Siebold of Erlangen, published by the Ray Society, are very insufficient for 

 the purposes of reference ; nor are all the anatomical investigations of M. 

 de Quatrefages and M. Blanchard within reach. 



The Circulating Fluids. — In the economy of all Annelids, one or two 

 species excepted, two distinct and separate fluid elements of nutrition exist ; 

 of which one consists of the proper and true blood, contained in closed vessels 

 and moving in a definite orbit, and constituting a well-marked circulation ; 

 the other of a liquid mass, filling the open space which, in all species, in- 

 tervenes between the intestine and the integument, holding organic corpuscles 



* Memoria sugli Anaelidi della famiglia delle Sanguisughe, in 4to, MUan 1837. 



t Descriptive and Illustrated Catalogue of the Physiological Series, &c. by Owen, vol. ii. 



X Memorie sulla storia i uotomia degli Animali senza vertebra del regno di Napoli, 

 torn. ii. and iii. 



§ The contributions of Dr. Johnston to this branch of natural history will be found dis- 

 tributed throughout the early series of the ' Annals and Magazine of Natural History.' In 

 treating of species, separate references will be made to this author's publications. 



II Recherches pour servir a I'histoire de la circulation du sang chez les Annelides, lues a 

 I'Academie des Sciences, le 30 Octobre 1837. 



f Art. Entozoa, Cyclopaedia of Anatomy and Physiology. 



