Dr. Johnston on the British Annelides. 373 



I have dedicated the species to Mr. Forbes's companion, 

 who is already well known to comparative anatomists by his 

 ingenious researches into the development and structure of 

 the teeth ; and who promises to recommend himself to the 

 gratitude of naturalists by an investigation of our native ra- 

 diated animals. 



The worm I am next to notice possesses a considerable de- 

 gree of interest, for some of the peculiar characters of three 

 families meet apparently in it, and it connects them more 

 closely than any genus hitherto discovered. The head reminds 

 us of the Echiurus, — a genus in the family Lumbricidce ; the 

 position of the mouth is much the same as in Cirrhatulus, and 

 there is some analogy between them in the structure of the 

 feet, while the anus resembles that of Nerinne, which, as well 

 as Cirrhatulus, belongs to the Ariciadce ; but then the form of 

 the body and its annular structure is that of Arenicola ; and 

 notwithstanding some obvious discrepancies, this worm ought 

 perhaps to be referred to the family of which Arenicola is the 

 type, though there is no genus in it with which the species 

 before us can be associated. I therefore propose to create a 

 new genus in the family for its reception, to which the name 

 Travisia may be given, in commemoration of Mr. Travis, an 

 eminent surgeon in Scarborough, and one of those " learned 

 and ingenious friends" to whose correspondence Mr. Pennant 

 was much indebted in preparing his British Zoology. 



Family Arenicolid^e. 



1. Arenicola. Mouth terminal; branchiae arbuscular. 



2. Travisia. Mouth ventral ; branchiae a simple filament. 



Travisia Forbesii. 



Plate XI. Fig. 11—18. 



In figure this annelide is something between that of the 

 earth-worm and the leech : it is elliptical anteriorly, narrower 

 and subcylindrical in the posterior half, of a uniform dull 

 olive-green colour, smooth to the naked eye, distinctly an- 

 nular. Both sides are so alike that it is not easy to say at first 

 which is the dorsal and which the ventral ; but the anterior 

 segments are so far unlike the posterior ones, that, to render 



