732 RECOED OF CURRENT RESEARCHES RELATING TO 



In the Chjmenkv. the corjwra Bojani are very long ; and at thcii" 

 anterior extremity tlio segmental organs arc attached. After the 

 eleventh segment there are no longer any renal bodies, and in their 

 place there is a plexus of blood-vessels of remarkable abundance. 

 The position of these networks is such that we may say that they 

 represent so many corpora Bojani formed solely by their vascular 

 frameivorJc. 



The ovum of these animals is remarkable for the separation into 

 two parts of the vitelline mass ; one of these, the larger one, is formed 

 of large granules, the other of very small ones. In the latter is 

 situated the germinal vesicle and the spot, which becomes strongly 

 coloured by picro-carminate. 



Pcctinaria helgica exhibits first a pair of very iarge corpora Bojani, 

 and then two pairs furnished with segmental organs. The genital 

 gland is on the median line, on each side of the supranervous vessel. 

 The animal is as transparent as glass ; and notwitlistanding this the 

 segmental organs cannot be perceived. It is curious that in less 

 transparent animals these organs have nevertheless been observed by 

 translucence and figured. 



With regard to the segmental organs in the errant Annelides, we 

 find a pair of them in each segment, with a contorted tube having an 

 internal pavilion and an opening outwards. In the Serpulidae (a 

 family very rich in genera), among the sedentary forms, the same 

 thing is met with. Lastly, in all the other Sedentaria we find the 

 segmental organs sometimes free, sometimes annexed to the corpora 

 Bojani, and in the majority of cases we may say that the segmental 

 organs are indejiendcnt of those bcdies. 



Hitherto we have been acq[uainted with three species of herma- 

 phrodite Spirorhis ; a fourth must be added, namely, Spirorbis communis, 

 which abounds at Eoscoff". 



In the group Gejihyrea, in Phascolosoma vulgare, we find on the 

 anterior part of the two long blackish sacs, a tube furnished with a 

 pavilion with two broad ciliated lips. The structure of the sacs 

 shows them to be renal bodies, to which the segmental organs are 

 annexed. The genital gland, male or female, is situate at the base of the 

 posterior pair of the retractor muscles of the proboscis. The racemose 

 gland is attached to an elastic thread, which is probably a blood- 

 vessel. The ovum is remarkable for the presence of cilia at the 

 surface of the vitelline membrane, which, when observed in front, 

 appears finely striated. 



lu the subiutestinal blood-vessel, in the midst of the elliptical 

 blood-globules, we find encysted trematodcs, which are carried along 

 even into the papillfe of the proboscis, by the cilia with which the 

 vessel is furnished. The above-mentioned papillfe appear to play a 

 great part in respiration ; in fact the whole circlet is in communica- 

 tion with the circulatory apj^aratus. The globules ascend along the 

 walls, and descend by the centre of the papilla. Processes of the 

 wall in the interior of the papillary cavity cause the globules to 

 remain a certain time in contact with the delicate wall of these 

 organs, and thus facilitate an exchange of gases. This may exjilain 



