74 VERMES. 



Motion smooth and gliding, the body being completely extended. If 

 reversing its course, the animal folds on itself. 



While crawling, occasional swellings of the body are seen, with pro- 

 portional reductions which disappear as the linear form is resumed. 



PLATE X. 



FIG. 5 a. Gordius albicans. 



6. Head, enlarged ; shewing the superficial specks. 



B. GORDIUS GRACILIS. To preserve some connection in this subject, 

 I shall here advert to another animal of this tribe, though it may not 

 prove to be exactly in its place, under the denomination of Gordius gra- 

 cilis. Plate IX. fig. 8. 



This animal extends three inches in length, in a roundish form, 

 scarcely above the twelfth of a line in breadth or diameter. In motion 

 it becomes as slender as a fine white horse hair, the extremity scarcely 

 visible. The anterior part, when contracted, is reddish, fading gradually 

 downwards to white. The whole, if coiled up, is faint carmine ; but ex- 

 tended, it seems white. 



No specks or eyes could be discovered. This species feeds greedily 

 on mussel, sucking it by the mouth, which is below, near the anterior 

 extremity ; and drags the food to the place of its own retreat. 



Five or six specimens were taken on June 11, one of which, on the 

 20th, emitted a rope of spawn proportionally as large as that of the species 

 just described. It was in a fold half an inch long, therefore an inch if ex- 

 tended : the breadth of the fold nearly half a line. Under the microscope 

 the ova were white, opaque, not quite spherical, immersed in a transparent 

 substance ; all as seen two days afterwards, fig. 9. In a few days a num- 

 ber of animalcula were produced by the ova. I could ascribe them to 

 no other origin, and that such was the case, was proved by the identity of 

 those contained in the ova, and such as were free. Those creatures ap- 

 peared mere specks in the water, swimming with considerable expedition. 

 Keeping chiefly below, both in a vessel and in a watch-glass, they con- 

 gregated towards the side farthest from the light, which induced me to 



