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Show 410 ON A RECENTLY DISCOVERED TURBELLARIAN WORM. [Mar. 1, indication of its habit-this being the first recorded parasitic Accel (in.)-I suggested incola as the specific name. NOTE ON THE PROPORIDAE. V. Graff in his recent monograph (i.) divided the Proporidae- Accela with one genital pore-into two genera : (a) Proporus, (b) Monoporus. In both these the male and female ducts open into a common atrium genitale which communicates with the exterior by a single aperture. They are distinguished from each other by the absence and presence respectively of a spermotheca. Since then (1890) some further contributions have been made to our knowledge of this family. In 1892 v. Graff (n.) drew attention to the turbellarian characters of Haplodiscus piger (Weldon). In 1895 Bohmig (iv.) described six new species of this genus and corroborated Weldon's observation of the absence of female accessoria. The following year Sabussow (v.) recorded another species, on which also Monticelli wrote (vi.). In 1899 Sabussow (v.) obtained from the White Sea an Accel to which he gave the name Bbhmigia maris-albi (vn.). Bbhmig's classification of the family is as follows:- " Genera-(a) Monoporus-Proporidae mit Bursa-seminalis, &c. (b) Proporus-Proporidae ohne Bursa-seminalis, &c. (c) Haplodiscus-Proporidae ohne Bursa-seminalis. Die Mundoffnung findet sich in oder hinter der mitteder Bauchflache. Der Pharynx ist, wenn vorhanden, kurz und wenig entwickelt. Der Korperform ist platt scheibenformig." He thus distinguishes Proporus and Haplodiscus merely by the position of the mouth, the size of pharynx, and shape of body, while he ignores the absence in Haplodiscus of the "atrium genitale " in the other two genera. Now it has been shown above (p. 409) that in Avagina the female apparatus is incomplete, the ova being extruded through a temporary opening which has no connection with that of the male organ. As in Haplodiscus there is a similar absence of vagina, it seems not improbable that a like method of ova-extrusion also obtains. The union of the male and female systems to form a common genital atrium in the genera Proporus, Monoporus and Bbhmigia, and their total separation in Haplodiscus and Avagina, seem to render desirable a subdivision of the family as under:- Family PROPORIDJE : Accela with one genital aperture. Subfamilies I. Proporince: to include those Proporidae with a common genital atrium. Genera : (a) Proporus, (b) Monoporus, (c) Bbhmigia. II. Avaginince : to comprise those Proporidae with male accessoria only. Genera : (a) Haplodiscus, (b) Avagina. |
