VERMES. 79 



A fine specimen, about eight inches long, had the spinous prolonga- 

 gation extending about a quarter of an inch. This prolongation appeared 

 somewhat muricate under the microscope. Another specimen, four inches 

 long, was of a deep red purple, all except the anterior margin, which 

 appeared yellowish. Its prolongation rather exceeded a quarter of an 

 inch. 



A thin specimen extended about three inches, and the prolongation 

 half an inch more. The colour of the anterior part was dark purple, but 

 about fifteen lines of the posterior, including the prolongation, pure white. 

 This latter portion had been undoubtedly a reproduction, as its com- 

 mencement proved somewhat smaller than the dark part, which was 

 nearly two lines thick. The specimen came from Shetland. It must 

 have been large originally. 



Very faint circles were just perceptible on the body at considerable 

 intervals. In certain positions there is an indistinct appearance of an- 

 nulation in some of this flattened race. 



PLATE XI. 



FIG. 2. Gordius purpureus spinifer. 



3. Head of the same, slightly enlarged. 



4. Posterior extremity. 



c. GORDIUS FRAGILIS SPINIFER. Plate XI. Fig. 5. 



Total length three inches and half, of which the spine equals half 

 an inch ; breadth two lines. Colour universally reddish-orange, unless 

 a small portion of the posterior extremity, which alone with the spine 

 was white. This probably indicates reproduction of a mutilated speci- 

 men, which must have been of more ample dimensions, especially when 

 we allot above half an inch to the spinous prolongation. 



This specimen shewed some peculiarities which I had not observed 

 of others ; such as forming a very slight silken sheath, and the head 

 tapering almost to a point when the animal was in motion. In quies- 

 cence, the lower portion was much broadened. One or more enlarge- 



