79. MATERIALS FOR THE KNOWLEDGE OF THE CENOZOIC NON-MARINE MOLLUSCA OF NORTH CHINA (Part 1)

Abstract

The fossil gastropods dealt with in the present paper were collected by Dr. Tetsugoro WAKINIIZU from the loess at Tsingsing and Shihkiachwang (the socalled “red eposited loess”?), both in Hopei Province.
The material from Tsingsing comprises only three species as follows:
Brailybacna (Manchurohclix) lavrushini (COCKERELL)(2 specimens)
Cathaica fasciola (DRAPARNAITD)(4 specimens)
Cathaica putvcratrix (von, MARTENS)(2 specimens)
Bradybacna lavrushini still lives in this district and the two species of Cathaica are most common snails in North China, both fossil and living. The state of preservation of the fossils is very excellent.
The collection from Shihkiachwang contains three species of fresh-water gastropods and two of land snails, as listed below:
Lymnaca (Galba) pervia von MARTENS (about 10 specimens)
Lymnaca (Radix) plicatula BENSON (3 specimens)
Anisus (Gyraulvs) sp.(1 specimen)
Opeas pyruala SCHMACKER and BOETTGER (7 specimens)
Metodontia yavtaiclisis (CROSSE and DEBEAUX)(6 specimens)
All the species are now widely distributing throughout North China. Most of the specimons before hand are not well preseived.
The detailed synonymy, the dimensions, the recent distribution and the fossil occurrence of each species are shown in the foregoing pages. Further, a tentative correlation table of the Cenozoic formations in North China and Manchuria is given on page 92, detailed discussion of which, however, will be reserved for another occasion.
The results of the taxonomic studies are summarised as follows:
1) Limnaea (Gulnaria) shantungensis JONES and PRESTON (1904), Limnaea kingi PING and YEN (1933), Limnaea truncatula tenua PING and YEN (1933) and Galba laticallosiformis YEN (1937) are all synonyms of Lymnaea (Galba) pervia von MARTENS. The specimens of Lymnaea from South Ordos being referred to Galba truncatula (MÜLLER) by YEN (1937) are also identifiable with pervia, while Limnaea exigua PING and YEN (1933) described from Aksu evidently belongs to Lymnaea (Galba) truncatula (MÜLLER).
2) Limnaeus chefouensis CLESSIN (1886), Limnaeus möllendoKtflanus CLESSIN (1886), Limnaea mars JONES and PRESTON (1904) and Limnaea whartoni JONES and PRESTON (1904) may be synonymous with Lymnaea (Radix) plicatula BENSON.
Further, the specimens from Tai-hu being assigned to Limnaea clessini NEUMAYER by ANNANDALE (1918) undoubtedly belong to plicatula, and the shells referred to clessini by YEN in -his recent paper (1937) on gastropods of. North China seem more closely related to plicatula than to NEUMAYER'S species.
In the Ryûkyû Islands, there is inhabiting a form of Lymnaea which can hardly be distinguished from plicatula. Many Japanese authors have referred it to Limnaea minor BENSON, but this identification does not seem reliable. In his description of minor, BENSON has given neither its illustration nor dimensions and has stated that it strongly resembles Lymnaca (Galba) truncatula (MÜLLER). This species has never been reported from the Asiatic Continent, since it was first described from the Chusan Islands.
3) Opeas fragilis PING (1929), a fossil species from the Choukoutien formation, is nothing but a synonym of Opeas pyrotla SCIIMACKER and BOETTGER.
4) A detailed description of Bradybaena lavrushini (COCKEREL') is given by Isao TAKI in a paper entitled “Mollusca of Jehol”(Report of the First Scientific Expedition to Manchoukuo, section 5, division 1, part 1, article 4) which will be published in the near future.