DESMOSCOLECIDA  , a

group of minute marine worm-like creatures . The body tapers towards each end and is marked by a number of well-defined ridges . These ridges resemble on a small scale those which surround the body of a Porocephalus (Linguatulida), and like them have no segmental significance . Their number varies in the different species . The head bears four setae, and some oI the ridges bear a pair either dorsally or ventrally . The setae are movable . Two pigment spots between the fourth and fifth ridges are regarded as eyes . The Desmoscolecida move by looping their bodies like geometrid caterpillars or leeches, as well as by creeping on their setae . The mouth is terminal, and leads into a muscular oesophagus which opens into a straight intestine terminating in an anus, which is said to be dorsal in position . The sexes are distinct . The testis is single, and its duct opens into the intestine and is provided with two chitinous spicules . The ovary is also single, opening independently and anterior to the anus .

The

nervous system is as yet unknown . There are several species . D. minutus Clap. has been met with in the English Channel . Others are D. nematoides Greef, D. adel phus Greef, D. chaetogaster Greef, D. elongatus Panceri, D. lanuginosa Panceri . Trichoderma oxycaud alum Greef is o•3 mm. long, and is also a " ringed creature with long hair-like bristles." The male has two spicules, and there is some doubt as to whether it should be placed with the Desmoscolecida or with the Nematoda . With regard to the systematic position of the group, it certainly comes nearest—especially in the structure of its reproductive organs—to the Nematoda . We still, however, are very ignorant of the internal anatomy of these forms, and until we know more it is impossible to arrive at a very definite conclusion as to their position in the animal kingdom . See Panceri, Atti Ace . Napoli. vii . (1878) ; Greef, Arch . Naturg . 35 (i.) (1869), p .

112 . (A . E .