Dr Grant o?i the structure of the Lerncea elongata. 147 



Art XXXII. — On the Structure and Characters of the Ler- 

 ncea elovgata, Gr. a New Species Jrom the Arctic Seas. 

 By R. E. Grant, M. D., F. R. S. E., Fellow of the Royal 

 College of Physicians ofEdinburgh, and formerly Lecturer 

 on Comparative Anatomy. Communicated by the Au- 

 thor. 



1 HE various classes of animals spread over the globe, whe- 

 ther inhabitants of the dry land, or of lakes and rivers, or of 

 the atmosphere, or dispersed through the vast abyss of the 

 ocean, find in the rich and varied clothing of organic matter 

 covering the nakedness of the earth, sufficient nourishment 

 not only for their own subsistence and growth, and for the 

 continuance and multiplication of their species, but likewise 

 sufficient to enable each individual to support various tribes of 

 parasitic inhabitants. Innumerable species of Insects^ Arach- 

 nidoe, and Annelides move to and fro on the surface of their 

 bodies, feeding on the excreted matters of the skin, or sucking 

 the vital fluids from the interior. Various kinds of ova are 

 deposited, matured, and hatched under the skin, although the 

 animals they contain are not destined to a parasitic life. An 

 immense variety of Worms live and propagate, imbedded in 

 the muscular and cellular tissues, in the internal cavities and 

 vessels, and in the parenchymatous substance even of the best 

 protected organs of the body. And various fluids and secre- 

 tions of the living system contain myriads of Infusoria. The 

 class of Worms, to which the following undescribed animal is 

 considered as most nearly allied, contains the most remarkable 

 forms, and the greatest number of species of parasitic animals ; 

 and from their ravages in the living body of man, and of the 

 animals most subservient to his wants, from the very equivo- 

 cal nature of their origin, and from their singular forms, 

 structure, and habits, these species have engaged the particu- 

 lar attention of many distinguished naturalists, as Redi, Le 

 Clerc, Muller, Bremser, Rudolphi, &c. Although most pa- 

 rasitic worms live entirely imbedded in the animals on which 

 they feed, the remarkable tribe of epizoariw to which the Ler- 

 naa belongs, are found only attached to the surface, or par- 



