78 VERMES. 
latter feature, have rendered it difficult to credit that all were mutilated, 
and that none were entire. 
Nevertheless, with animals so readily exposed to mutilation, and 
whose reproductive faculties are so energetic, it is impossible to avoid 
perplexities regarding their integrity. 
Some of the preceding specimens were preserved a long time with- 
out any symptoms of regeneration ; yet their resemblance to the subjects 
of this paragraph, with a spinous prolongation, is so close, that I must 
almost consider the description of both only as provisional. 
Specimens distinguished by the eaudal process, however, are not 
nearly so common as the others, on the contrary, they may be accounted 
rare. 
a.—GORDIUS VIRIDIS SPINIFER.—Plate XI. Fig. 1. 
Length about three inches ; head and body resembling those of the 
Gordius minor viridis already described, the groove being very distinct. 
The posterior extremity terminates in a retractile, spimous, or cartilagi- 
nous prolongation, and equalling about a sixth of the length of the body. 
Colour mountain green. 
The spinous prolongation is a spontaneous protrusion, that is, it can 
be retracted completely, especially when the animal is at rest, and when 
gliding along it is drawn out to the slenderness of a human hair, actually 
becoming invisible from extreme tenuity without a lens, or being placed 
ona black ground. ‘This prolongation is very flexible, forms various 
curvatures, and displays peculiar action independently of the body. 
Piate XI. 
Fic. 1. Gordius viridis-spinifer. 
b.—GORDIUS PURPUREUS SPINIFER.—Plate XI. Figs. 2, 3, 4. 
Among several specimens there has been scarcely any other distinc- 
tion than colour ; nor can I venture to specify what may be the dimen- 
sions of the species. 
