292 APPENDIX. 



may proceed from some difference in food, or in its state of repletion. 

 The resemblance between it and the Planaria rosea of Miiller {Zool. 

 Ban. tab. 64. f. 1, 2) is sufficiently great to suggest a suspicion of 

 their identity, but Miiller expressly states that the latter is destitute 

 of eyes (see the Prod. Zool. Dan. p. 221). 



Omatoplea melanocephala (page 23). 



Body from 1 to ll inch long, narrow and vermiform, tapered at 

 the tail, of an olive or yellowish colour, the latter tint most predo- 

 minant in front, which is marked with a black spot of a quadran- 

 gular form, and four eyes placed nearly in a square. It was in this 

 species that the structure peculiar to the genus was most easily to be 

 traced. 



Omatoplea pulchra (page 24). 



Body about an inch in length, and two lines in breadth, com- 

 pressed, narrow, elliptical, the front marked with numerous black 

 specks, irregularly arranged, and visible with the naked eye. Many 

 specimens are of a uniform avirora-red colour, considerably paler on 

 the ventral aspect, while others are beautifully marked along each 

 side with a series of large scarlet spots; the former are perha])S 

 males, or more probably individuals in a barren condition, while the 

 others ^eem to be full of mature ova, for an examination of the spots 

 through the microscope shows that they are produced by clusters of 

 oviform bodies lying in the interstices of the csecal appendages. 



This and the first species contrast remarkably in their form, and 

 show the extremes to which this character is subject. The structure 

 of the stomach is like that of its congeners, excepting in there being 

 five or six spines on each side of it, instead of three, which is the 

 usual number. Immediately under the hearts we observe a large, 

 somewhat muscular viscus, apparently hollow, and lying in the course 

 of the intestine, but seemingly unconnected with it ; for in the indi- 

 vidual examined, the intestine had been extruded from the body, and 

 entirely expelled by the contortions of the worm produced by impure 

 sea-water. Of its office and nature I can offer no opinion, but I 

 may remark that in all the species a greater duskiness in its site 

 shows that a similar organ exists in all. 



Stylus viridis (page 24). 



" The spinous prolongation is a spontaneous protrusion, that is, it 

 can be retracted completely, especially when the animal is at rest ; 

 and when ghding along, it is drawn out to the slenderness of a human 

 hair, actually becoming invisible from extreme tenuity without a 

 lens, or being placed on a black ground. This prolongation is very 

 flexible, forms various curvatures, and displays peculiar action inde- 

 pendently of the body." — Dalyell. 



