Ml'. W. H. Benson on a new Species of Helix. 175 



Fig. 15. The same, with one division of the spore abortive. 



Fig. 16. The same. Sporangial frustule surmised to be of the size pro- 

 duced by these conjugations. In all these frustules the spe- 

 cific characters are too small to be delineated on the scale to 

 which they are drawn, although perfectly distinct under the 

 microscope. 



Fig. 17- Pinnidaria gibba, Ehr. In conjugation. The pelHcle of the 

 gelatinous secretion and the ends of the capsules absent. 



Fig. 18. The same ; more advanced stage. The valves of one of the con- 

 jugating frustules absent. 



Fig. 19. The same. Relative size and form of conjugating frustule, 



Mg. 20. The same. Full size of sheath of sporangial frustule in this 

 gathering. 



Fig. 21. The same. Full size of frustule produced by these conjugations. 



XIX. — Description of Helix odontophora, a new Species of the 

 Gorilla type, from Upper Ouvah, in Ceylon, By W. H. Ben- 

 son, Esq. 



Helix odontophora, va\\a, n. sp. 



JJ^ testa late umbilicata, rotmidato- vel ovato-discoidea, solidula, 

 castanea vel rufescenti-lutea, superne subplanulata, oblique 

 tenuiter costulato-striata, subtus valde coneava, striata, nitida; 

 spira planiuscula, versus apicem obtusum elevatiore, sutura im- 

 pressa ; anfractibus 4, primis convexiusculis, ultimo antice con- 

 vexiore, turn descendente, dilatato-deflexo, subtus valde inflate; 

 apertura perobliqua, obtuse subcordata, lamellis 2 parietalibus 

 (superiore longe intrante curvata, inferiore subparallela, breviore, 

 subcurvata, ab apertura remotiuscula), palatalibus 4 brevibus 

 semilunaribus vel sinuatis (omnibus integris ab apertura conspicuis, 

 extus perlucentibus) coarctata ; peristomate purpurascenti-albido 

 vel castaneo, calloso, breviter reflexo, marginibus superiore et in- 

 feriore subdentato-incrassatis. 



Diam. major 26, minor 19, alt. 8 mill. 



Habitat in montibus Cejdanicis prope Fort McDonald, Bandarewella, 

 et Bibiligamua ad altitudinem ped. 4500. Teste Dom. F. Layard. 



The examination of a broken specimen of a shell, supposed 

 to be H. erronea, which I received from Mr. F. Layard, with the 

 internal lamellae fully exhibited, convinced me that a peculiar 

 type had been overlooked ; and Mr. Layard kindly forwarded to 

 me the shells which he referred toH. erronea from Upper Ouvah 

 and Pusilawe : the latter all belong to the true erronea type, 

 with three parietal and four lengthened palatal lamellae, also a 

 single specimen out of five from Bandarewella; the rest all 

 prove to be H. odontophoraj with only two parietal lamellae and 

 more delicate sculpture (as in H, Anax, mihi, and H. Humherti^ 

 Brot), only four whorls, and short semilunar or sinuate palatal 

 lamellae entirely visible from the aperture, — the Fort McDonald 



