Annelida of St. Andrews. 151 



Fam. 2. Schizostomea, O. Schm. 

 Genus Convoluta, QErst. 

 Convoluta paradoxa, Abildgaard 5 Jolinst. Cat. p. 16. 

 Very common amongst seaweeds and Corallina in tide- 

 pools. 



Convoluta Diesingii, Schmidt (?), Sitzungsb. der k. Akad. 1852. 

 Occasionally under stones in rock-pools. 



Fam. 3. Mesostomea, O. Schm. 



Genus Mesostomum (Duges),M. Sch. 



Mesostomum bifidum, n. sp. 



On the under surface of stones from low-water mark, East 

 Rocks. One tenth of an inch long, and of a very pretty pale 

 orange hue. The body is pointed anteriorly, dilates in the 

 middle, and diminishes posteriorly, terminating in two pro- 

 cesses which have a few rather large papillae on their crenated 

 edge ; these papillae seem to have a slight sucker-action. 

 There are two semilunar eyes, with the concavity external. 

 The cilia are specially distinct a little behind the snout, on 

 each side, at points corresponding to the long ciliary whips of 

 the developing Nemertean. The male organ formed a spirally 

 marked conical process behind the large median sucker ; and 

 the testes were loaded with spermatozoa in various stages of 

 development. 



Fam. 4. Derostomea, (Erst. 

 Genus Voetex, Ehrenberg. 



Vortex capitata, OErst. Entwurf Plattwiirmer, p. 65, 



pi. 1. f. 7. 



Occasionally under stones between tide-marks. Many dia- 

 toms occur in the digestive canal. 



Fam. 5. Opistomea, 0. Schm. 

 Genus Monocelis, Ehrb. 



Monocelis unipunctata (Fab.), (Erst. Ent. Plattw. p. 56. 



This appears to be the Planaria flustrce of Dalyell. It is 

 abundant under stones between tide-marks. 



