Ii8 DESCRIPTIONS OF PREPARATIONS. 



culum seminis, and in this species it is said to undergo resolution in ten days after 

 transference. The dart-sac, which has extremely muscular walls, contains a pointed 

 cuticular style, with much calcareous matter in its composition. Its use appears 

 to be a preliminary excitant to copulation, after which act it has been found within 

 the body. A new dart is speedily formed after the loss of the old one. The 

 multifid vesicles secrete a highly refractile fluid, which is poured out during co- 

 pulation, and is formed by the epithelium. The duct of the receptaculum seminis has 

 occasionally a tubular diverticulum appended to it. The latter is constantly present 

 in many species of the genus Helix, e. g. H. aspersa, and may possess a terminal 

 bulb like the receptaculum itself. The genital organs are richly supplied with 

 nerves and bloodvessels. In aquatic Pulmonata the male and female apertures 

 open separately from one another externally. 



Of the accessory organs present in Helix pomatia, the flagellum is absent in 

 all the American species of the genus, and both dart-sac and multifid vesicles, 

 common in the European species, are rare in them. A dart-sac is found in the 

 American slug Tebennophorus ; and glands resembling -the multifid vesicles are 

 appended to the male organs in Veronicella. With these two exceptions the 

 organs in question are confined to the genus Helix. 



The eggs have, like those of other Helices, of Arion and some other terrestrial 

 Pulmonata, a hard calcareous shell inclosing a quantity of albumen and a small 

 ovum. Those of some terrestrial (Limax\ and of all aquatic Pulmonata, 

 are devoid of a calcareous shell, and the surface of the albumen is simply hard- 

 ened. The eggs of H. pomatia are large, nearly a quarter of an inch in size, and 

 are laid in earth as are those of other terrestrial Pulmonata, in masses, but not 

 united, as are those of many species of Limax and of all aquatic Pulmonata. 

 A few terrestrial Pulmonata are viviparous (certain species of Clausilia and Pupa, 

 Helix rupestris, Achatinella, a Vitrind). The larva has but slight traces of the 

 typical Molluscan velum ; in that point differing from its aquatic congeners, where 

 it is well developed, and Arion and Limax, where it is wanting. There is no 

 operculum. A remarkable contractile pedal sinus is present. A paired provisional 

 tubular renal organ appears to be found in the larva of all Pulmonata. 



Integument. Leydig, A. N. 42, 1876. Epithelium. Flemming, A. M. A. vi. 

 1870. Connective tissue (interstitial}, Brock, Z. W. Z. xxxix. 1883. 



Odontophore. Mechanism. Geddes, Tr. Z. S. x. Radula, Rossler, Z. W. Z. xli. 

 1885. Description of various forms of dentition and nomenclature, Gray. P. Z. S. 

 1853; A. N. H. (2), xii. 1853; Troschel, Das Gebiss der Schnecken, Berlin, i. 

 1856-63; ii. parts i-vi. 1866-79. Myohaematin in odontophore muscles, MacMunn, 

 Proc. Physiol. Soc. in Journal of Physiology, v. 1884; P. R. S. xxxix. Novr. 1885. 



Salivary glands, &c., see Nalepa (op. cit. ante, p. 112). Sugar formation. 

 Bonardi, Boll. Sc. Pavia, Anno 5, 1883. Liver Barfurth, A.M. A. xxii. 1883 ; Id. Biol. 

 Centralbl. iii. 1883-84; Frenzel, Biol. Centralbl. torn. cit. j Id. A. M. A. xxv. 1885 ; 

 its physiological action, Krukenberg, Untersuchungen Physiol. Inst. Heidelberg, ii. 

 1882, pp. 4 and 13 ; Fredericq, Bull, de 1'Acad. Royale de Belgique (2), 46, 1878. 

 Pigments. MacMunn, P. R. S. xxxv. 1883, and xxxviii. 1884-85 ; Krukenberg, Ver- 

 gleich. Physiol. Studien, ii. (2) p. 63, 1882. Glycogen, Barfurth, A. M. A. xxv. 1885. 



Genital organs, Baudelot, A. Sc. N. (4) xix. 1863. Histology of accessory organs, 

 Batelli, Atti Soc. Toscana Sc. Nat. (Mem.), iv. 1880 ; cf. Journal Royal Micr. Soc. 



