Vörös A. szerk.: Fragmenta Mineralogica Et Palaentologica 14. 1989. (Budapest, 1989)
characters: Tropeothyris islarensis has a suberect to erect umbo, the shell is inflated with an elongated triangular posterior part, its maximum width is at the mid-line. Loriolithyris cf. valdensis differs from Loriolithyris russilensis in being larger, more elongated and flattened, and more markedly uniplicate. It can be separated from the variant of MOISSEEV on the wider and flattened shell with a slightly sulciplicate anterior margin. Distribution: Neocomian of Morocco and Algeria; Valanginian of the Jura region and the Paris Basin; Hauterivian of Yonne (France); Barremian of Basses Alpes and Alpes Maritimes; Aptian of western Switzerland and north-eastern Spain. Subfamily Sellithyridinae Genus Praelongithyris Middlemiss, 1959 Praelongithyris aff. praelongiforma Middlemiss. 19 59 (Plate II: 13-20) Material: 1 complete juvenile and 1 complete adult specimen and 4 pedicle valves from the Szilas-árok. 1 pedicle valve from the Eperkés-hegy. Dimensions (mm): L 12. 6 20 W 9. 9 14 T 6 (juvenile) 11 Description : The shell is elongated egg-shaped in outline, much longer than wide, strongly inflated. P/A ratio is always more than 1:1, sometimes 1. 5: 1. Maximum thickness is at the mid-line. The umbo is suberect with long but poorly marked beak ridges and circular, mesothyrid to permesothyrid foramen. The brachial valve is evenly convex. The lateral comissure runs straightly ventralwards, then, in the anterior quarter of the shell, turns dorsalwards. The anterior comissure is sulciplicate. There is a complete juvenile specimen in the material. The biconvex shell is oval in outline with triangular posterior and round* ed anterior parts. The maximum thickness is at the posterior third. The brachial valve is rather flat with maximum convexity near the umbo. The umbo is erect, slightly elongated. The circular foramen is mesothyrid. The short deltidial plates are well visible. The lateral comissure is archied, the anterior one is uniplicate (Figs. 14-15). (Figs. 14-15) Fig. 14. Praelongithyris aff. praelongiforma , juvenile specimen a= lateral view; b= anterior view Fig. 15. Praelongithyris aff. praelongiforma , adult specimen a= lateral view; b= anterior view Remarks : It differs from Praelongithyris praelongiforma Middlemiss, 1959 in being smaller and is having smaller foramen. The foramen does not seem to be labiate - perhaps due to the bad preservation. The anterior margin is straight to sulciplicate. It also differs from adults of Praelongithyris credneri Middlemiss, 1976 in having a higher P/A ratio, a sub-erect umbo and a deflnetely smaller size. However, it agrees with the juvenile specimen described by MIDDLEMISS. The author notes that juvenile forms of P. praelongiforma can not be distinguished from P. credneri. MIDDLEMISS considers the previous to be the descendant of the latter. For correct determination of the Bakony form, more and better specimens and transverse sections are required. Distribution : Valanginian and Hauterivian of England and Germany.
