515
4 Gen. Polystemma (Ehrb.) Oerst. with nine species.
(3. Oculi 8-16, biseriati.
5 Gen. Nemertes (Cuv.) Oerst. with twenty-eight species.Among others Oerstedt places here the worms described asPolia, Meckelia, Notospermus, Tubulanus.
■y. Oculi four.
6 Gen. Tetrastemma, Ehrb. with thirteen species.
(3.) Corpus lineare-oblongum depressum, utrinque sequa-liter obtusum, fissime respiratorise distinct®.
7 Gen. Cerebratulus, Ren. with two species.
Fam. II.— Amphiporina. Tubi cibarii utraque aperturaterminalis opposita.
8 Gen. Amphiporus (Ehrb.) Oerst. with one species. Ofthe species described, twenty-one belong to the coast ofDenmark , amongst which, fourteen quite new species occur.
Rathke (Nov. Act. Acad. Nat. Car. &c., t. xx. p. 231)has given the diagnosis of the Borlasia striata, previouslydescribed by him, as follows : oculis 16 (aut 18 ?); corporegracili, subdepresso; striis longitudinalibus nigrescentibuset subflavis alternantibus. To this is also added a newspecies, viz. Borlasia rufa: oculis 6; facie superiori convexarufa, inferiore plana flavescente. Rathke could not pro-cure, in a state sufficiently perfect to allow of their diagnosesbeing determined, two species of Meckelia, which, like theM. somatotomus described by Leuckart, were able to dis-member themselves with facility. Besides these worms,Rathke has designated another, also found on the coast ofNorway , under the name of Ramphogordius lacteus, pro-bably belonging to the Gordiacese. Its very slendercylindrical body terminates anteriorly in two minute pro-cesses representing a proboscis, between which the oralaperture is situated. Lateral depressions, organs of sense,and ah opening for the passage of the long vermiform organare wanting. The intestine, which is adherent to the abdo-minal cavity, presents posteriorly several longitudinal folds,and the abdominal nervous system is composed as in Borlasiaof two lateral chords.