128 AMPHINOMENACE^. 



beyond the skin. The ridges are regular and equidistant, and are 

 continuous with the feet on each side. The feet form a close-set 

 range round the body, interrupted only in front by a very narrow 

 fissure, in which the mouth is situated. They are all alike, short 

 and equal, formed of a single thick stump armed with a brush of 

 bristles (fig. 10) that project very little beyond the margin, and are 

 all glued together by a sort of albuminous membrane. There did 

 not seem to be any cirrus above the foot, but at the root of each of 

 them underneath there is a cirrus shorter than the foot itself, and 

 with a large bulb at the base (fig. 11). The bristles are of three 

 kinds; viz. (1) the spinous (fig. 12), sharp and fashioned like a 

 needle ; (2) the forked (fig. 1 3), which are filiform with a bulbous 

 root, and cut into two scarcely equal prongs at the apex ; and (3) 

 the clawed (fig. 14), a bristle which has a stem slightly incrassated 

 upwards, where a strong curved and sharp claw is articulated by an 

 oblique joint. The forked bristles are the most numerous ; and I 

 did not observe more than one clawed bristle in each foot, but there 

 were two or three from which the claw appeared to have been broken 

 away. There are no anal styles. 



I was indebted to my friend, the late "William Thompson, Esq. of 

 Belfast, for the specimen above described. It was half an inch in 

 length, with a breadth fully one-half of the long diameter. It had, 

 at the first glance, more resemblance to a Doris than to any Anne- 

 lid ; and when it was placed under a common magnifier, it was com- 

 pared, aptly enough, to the Cyprcea europcea, the comparison being 

 suggested by the similarity in the ridges that cross the back. 

 Another specimen, that had got soft by its maceration in a weak 

 spirit, was three-fourths of an inch long and three-tenths broad ; 

 and the ridges on the back were more hirsute, and divided by a 

 medial line. In this specimen the ventral surface was distinctly 

 annulated. 



The description is, in several respects, imperfect, but from the 

 distinctness of the worm as a species, it will sufiice for its future 

 recognition. Observations on living individuals seem necessary to 

 ascertain the number and nature of the oral appendages. That it is 

 a member of the family Amphinomenacese I infer from its general 

 habit, for it possesses few of the technical characters by which that 

 family has been hitherto defined ; and there is no one in the family 

 nearly allied to it. In common with the Palmyra, the back is naked 

 or without scales : there is nothing else in which the two genera 

 agree. 



Plate VI, Fig. 7. Spinther oniscoides of the natural size. 8. The 

 dorsal aspect viewed through a common magnifier. 9. A view of the 

 ventral surface. 10. Two feet detached, and viewed from the back. 

 11. A foot as seen from below. 12, 13, 14. The bristles. 



