Royal Society. 323 



death. In living and healthy persons, from one to three or four of 

 these entozoa are contained in each follicle. They are more nume- 

 rous in the follicles situated in the depression by the side of the 

 nose ; but they are also found in those of the breast and abdomen, 

 and on the back and loins. Their form changes in the progress of 

 their growth. The perfect animal presents an elongated bodj"-, di- 

 visible into a head, thorax, and abdomen. From the front of the head 

 proceed two moveable arms, apparently formed for prehension : and 

 to the under side of the thorax are attached four pairs of legs, termi- 

 nated by claws. The author distinguishes two principal varieties of 

 the adult animal ; the one remarkable for the great length of the 

 abdomen and roundness of the caudal extremity ; whilst the other is 

 characterized by greater compactness of form, a shorter abdomen, 

 and more pointed tail. The first variety was found to measure, in 

 length, from the one- 100th to the 45th, and the second, from the 

 one-160th to the 109th part of an inch. 



The author gives a minute description of the ova of these entozoa, 

 which he follows in the successive stages of their developement. 

 The paper is accompanied by numerous drawings of the objects de- 

 scribed. 



April 6. — " On the Structure and Developement of the Nervous 

 and Circulatory Systems, and on the existence of a complete Circu- 

 lation of the Blood in Vessels in the Myriapoda and the Macrourous 

 Arachnida." By George Newpoi't, Esq. 



This paper is the first of a series which the author proposes to 

 submit to the Royal Society on the comparative anatomy and the 

 developement of the nervous and circulatory systems in articulated 

 animals. Its purpose is, in the first place, to investigate the minute 

 anatomy of the nervous system in the ^Myriapoda and the Macrou- 

 rous Arachnida, and more especially with reference to the structure 

 of the nervous cord and its ganglia ; and thence to deduce certain 

 conclusions with respect to the physiology of that system and the 

 reflex movements in vertebrated animals ; secondly, to demonstrate 

 the existence of a complete system of circulatory vessels in the 

 Myriapoda and Arachnida ; and thirdly, to point out the identity of 

 the laws which regulate the developement of the nervous and circu- 

 latory systems throughout the whole of the Articulata, and the de- 

 pendence of these systems on the changes which take place in the 

 muscular and tegumentary structures of the body, as, in a former 

 paper, he showed was the case with regard to the changes occurring 

 in the nervous system of true insects. 



The first part of the paper relates to the nervous system. A de- 

 scription is given of this system in the Chilognatha, which the au- 

 thor was led, by his former investigations, to regard as the lowest 

 order of the Myriapoda, and approximating most nearly to the 

 Annelida. He traces the different forms exhibited by the nervous 

 system in the principal genera of that order, the most perfect of 

 which are connected on the one hand with the Crustacea, and on 

 the other with true insects. Passing from these to the Geophili, the 

 lowest family of the Chilopoda, which still present the vermiform 



