Royal Society. 389 



three very dark bro\vn, nearly black bands (one at the periphery, 

 one before, and one behind it) ; aperture posteriorly subsinuated, 

 white ; upper part of the shell with irregular radiating, broadish 

 white streaks. 



ROYAL SOCIETY. 



June 17, 1841. — " On the Organs of Reproduction and on the 

 Development of the Alyriapoda." By George Newport, Esq. Com- 

 municated by P. M. Roget, M.D., Sec. R.S. 



The author commences his paper by stating that great interest 

 attaches to the study of the INIyriapoda, from the already known fact 

 that their mode of development, by an increase in the number of 

 segments, is directly the reverse of that of true insects in which 

 the develoiDment of the perfect individual is accompanied by an ap- 

 parent diminution in the number of these parts. He remarks, that 

 although the development of the Myriapoda has already been ex- 

 amined by several eminent naturahsts, such as Degeer, Savi, Gervais, 

 and Waga, some of the most important facts relating to it havej 

 nevertheless, escaped their notice, and he proposes, therefore, to lay 

 before the Society the result of his own investigations on this sub- 

 ject, and also his examinations of the organs of reproduction. 



The paper is divided into four sections. In the first, the author 

 describes the organs of reproduction, and shows that the parts de- 

 scribed by Treviranus, both in the male and female Julus, are only 

 the eiferential ducts in the male, and the oviduct in the female ; 

 that in the former there are developed, from the sides of the efferen- 

 tial ducts, a large number of sacs, the structure of which he de- 

 scribes, and states his opinion that these are the proper secretory 

 organs in the male, but remarks that he has not been able to follow 

 out the organs to their fullest extent. In the female, he shows that 

 the oviduct described by Treviranus is covered by an immense num- 

 ber of ovisacs, each secreting only a single ovum ; that many hun- 

 dreds of these exist around the duct, a large proportion of which 

 never reach maturity, being retarded in their growth by the deve- 

 lopment of others immediately around them ; and that the ova, when 

 matured, are passed from the ovisacs into the duct, and are then all 

 deposited at one time. He adverts especially to the remarkable condi- 

 tion of the female oviduct being a single organ, throughout the 

 greater part of its extent, but having a double outlet ; and shows its 

 analogy in the internal portion of the organs to those of some in- 

 sects, and in its double outlet to the Crustacea and Arachnida. He 

 also institutes a comparison between the structure of the male and 

 female organs in this Myriapod, which, from their simplicity, admira- 

 bly illustrate the uniformity of origin of these structures ; more esj^e- 

 cially the analogy between the ovisacs in the female and the caeca in 

 the male, and also their conformity in the absence, in the latter, of se- 

 parate vesiculae seminales, and, in tlie former, of sjjermatheca. 



The second section is occuj)ied by a short account of the structure 

 of the ovum, in which the author observes the germinal vesicle and 

 macula. He notices especially the presence of the yelk in the car- 



