366 MR. F. E. BEDDARD ON A RARE [-^P^"- 28, 



Oligochfeta. On the first segment of one specimen the ventral 

 setfe were evident on both sides of the body, but showed an 

 inequality of development. On the right side there were two 

 setse, but both of them immature, the immaturity being unequal. 

 One of the setee was like the " Soies de remplacement " of other 

 segments. It was complete down to the node. The other seta 

 was merely a slender short rod of chitin. On the left side of the 

 body I only found one rudimentary seta, which was like the least 

 developed seta of the right side and merely a short slender rod 

 exactly of the same form and size. 



Text-fig. 76. 



Fhreatothrix cantahrigiensis. 

 Ventral pair of setse of segment I. 



The vascular system seems to present certain recognisable 

 difierences from that of Phreatothrix ])ragensis described by 

 Yejdovsky, and it is really mainly by reason of this that I venture 

 to create a new species for this Phreatothrix from Cambridge. 

 Yejdovsky has figured *'the way in which the dorsal vessel ends 

 anteriorly. It appeal's to bifurcate in the fourth segment and to 

 give off anteriorly to this point three pairs of lateral vessels 

 which join the ventral vessel. 



I found in an example, studied with a special view of elucidating 

 the mode of bifurcation of the dorsal vessel, a different arrange- 

 ment anteriorly. The dorsal vessel (text-fig. 77) divided quite 

 at the anterior end of the body, and the first pair of transverse 

 vessels uniting it with the ventral vessel arose from it some 

 way behind this point of bifurcation. On the other hand, these 

 two lateral vessels joined each half of the ventral vessel formed 

 by the splitting of the dorsal vessel some way before the lattei- 

 united to form the single ventral blood-vessel. This very con- 

 siderable difference appears to me to be quite of specific value, 

 and there is hardly room for an error so very considerable, either 

 on my part or on that of the Bohemian Professor. 



* Zeitschr. wiss. Zool. t. c. Taf. xxxix. fig. 2. 



