with an Account of their Habits. 249 



to the margin of the entire body : when the animal contracts itself, 

 the back is raised in slight ridges, corresponding with those rays. 

 This species, therefore, has four orifices on its under surface. Back 

 finely reticulated with brownish purple. Length 1 inch ; breadth 

 three-quarters of an inch. 



Hob. Under stones on the sea-beach, St. Jago ; Cape Verd Archi- 

 pelago (February). 



This species is exceedingly active and irritable in its habits : it 

 lives, like a Nereis, under stones firmly imbedded in the beach at 

 low-water mark. It has the power of adhering with great tena- 

 city to smooth stones : another allied species had the same power, 

 could also swim well by a vertical movement of its body, and fre- 

 quently rolled itself into a ball. 



With respect to the four orifices : I presume, as in the P. for- 

 mosa, the two anterior ones belong to the reproductive system. 

 The central orifice undoubtedly is the mouth : the posterior one 

 would naturally be thought to be the anus ; but I am doubtful 

 of this, considering the little globular body which was protruded 

 through it, and from the existence in the following allied genus 

 of a double mouth. 



Diplanaria (nov. genus). 



Alimentary orifice double, with two exsertile mouth -suckers. 

 Two genital orifices in the posterior part of the body. A large 

 forked ovarium (?). Ocelli in four groups, two superficial and two 

 more deeply seated. The characters here given appear to me 

 absolutely to require the institution of a new genus. 



Diplanaria notabilis. 

 Plate V. fig. 4. Under-side magnified. 



Body very much depressed, with the edges very thin ; anterior 

 extremity thrice as broad as the posterior. On the under surface, 

 towards the anterior extremity, there is a clear space, over which, 

 on the back, the ocelli are situated ; into this space, on all sides, the 

 branching, clear, intestinal cavities enter. Each intestinal cavity 

 generally bifurcates three times before its fine extremities reach the 

 margin of the body. Towards the posterior extremity there is a 

 second clear space (with the two orifices D and E), into which also 

 the surrounding intestinal branching cavities enter ; these two spaces 

 are united by two longitudinal clear spaces (obscured by ovules in 

 the drawing) passing on each side of the elongated, opake, white, 

 central organ. This organ, when the animal is contracted, has the 

 appearance represented in the drawing, namely of an internal, elliptic 

 mass, narrowing at each end, with deeply sinuated borders, and with 

 two external, perfectly closed orifices over it, as shown at (B) and 

 (C) . But when these two orifices are opened, from both of them 

 broad, shallow, saucer-like mouth-suckers are protruded, as repre- 

 sented at (F) ; these, when contracted within the body, appear united, 



Ann. § Mag. N. Hist. Vol.xiv. S 



