ON THE ZOOLOGICAT, STATION AT NAPLIW. 



2.M 



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|l884. 

 ration of 

 lal would 

 Idy ptili- 

 litions to 

 bscopical 



|e of tlio 



lis organ 



Is bi3lii<r, 



ribcd by 



ij to tbc 



lels, and 

 Id v/itb a 



most eluborato network of tubules lyin<,' for tho most pari witliiu the 

 muscular layers ni' tbo body wall. This network is continuous, tlio 

 portion lying on the ono side of the body with the portion lying on tho 

 other side in the n)edian ventral region, and is also continuous throughout 

 the length of the body in the region in which it occurs — i c, from the ninth 

 iiost-oral ganglion to tho nineteenth. 



The tubules collect at certain spots, and pass down to open. to tho 

 exterior without tho intervention of any vesiele. There are lU pairs of 

 such apertures plaecd in somites lU-l!' inclusive, upon the first annulus 

 of each somite. The apertures are thus metamcrically related to tho 

 funnels, a pair of apertures corresponding with caah pair of funnels. 



The orgfia in reality consists of a paired series of nej)hridia, each with 

 a funnel to the interior, and a pore to the exterior, and these nephridiii 

 differ from thosein llinulo, Cli'ji.si)n;c\v., in that they remain eonti]Ul()ll^. 

 those on the one side with those on the other, and each pair with tlio.Sf 

 in front and behind. 



Supposing, as we are probably justified in doing, that the organs 

 have arisen by a hollowing of branching mesoblastic cells, we have here 

 a structure which has only advanced upon this primitive condition in 

 developing metamerically repeated funnels and apertures to the exterior. 



I obtained but very few specimens of Bnatchelliov, 1 was, however, 

 able to demonstrate tho existence of a very similar nephridium in that 

 genus, but I believe far simpler, in that it has not developed any internal 

 funnels and has only a single pair of pores to tho exterior, these corre- 

 sponding to the most ])Osterior pair in I'oiitohdelhi. 



The commonest I'oiituhdella at Naples belongs to the species 1'. 

 muricata, but I obtained single specimens of perhaps two other species, 

 and a specimen which must ])robably form a new genus ; but I should 

 wish to become much more fully ae(|uainted with all tho varieties at 

 present known before entering upon anj- toxonomic questions in a grouj) 

 wliich presents considerable difficulties in this respect, the churactors of 

 most value in forming a systematic arrangement — the number of annuli 

 ill a somite, etc.- — being at present very inaccurately described. 



Since tho discovery of Ilaphihranrhiis, a new genus of ('apitobran- 

 chiate Annelids belonging to a small, but in many Avays very interesting 

 group, I have endeavoured to obtain as many members of the group 

 as possible, in oi-der to complete a comparative study of the group; this 

 I carried out fiirtlun* at Naples. I obtiiued species of Grid, Fahrlcid, nnd 

 AinphlgleiKi, and obtained new results w ah regard to the structure of these 

 forms. I may state hei'o that I have confirmed the observations of 

 Claparede, which have lately been doubted, as to tho arrangement of the 

 modified pair of ucphrldia Avhich serve as tubiparous glands, arul the median 

 position of their aperture to the exterior, in Ainphirjlentt. 



At the request of Professor Lankester, I undertook the investigation 

 of certain problems connected with the blood system of jMollusca and tho 

 supposed taking in and shedding out of water by these animals. I studied 

 SoUii k'ljuiuen, and entirely corroborated the results previously obtained 

 Jit Xiiples by F. Gr. Penrose, to the efl'ccfc that ordinary blood does not exist 

 in the pericardium of that animal, and so probably of other Lamelli- 

 branchs. This I demonstrated by means of serial sections which show 

 tho nucleated blood corpuscles lying in the ventricle, but absent from the 

 pericardium. 



^Y ith regard to the supposed taking in of water, I kept various forms, 



