40 Moll. 
MOLLUSCA. 
theory that the function of the spiculum ainoris is to stimulate the other 
individual in copulation by prolonged cuticular irritation ; the pecu- 
liarities of the species do not connect it directly with other forms, but 
point to an independent origin in Central Asia, the home of the genus ; 
Sim roth (5). 
Male genital organs of Helix and Zonites correspond, except as regards 
the flagellum ; the vagiua includes a glandular and a copulatorj' portion. 
In Zonites the glandular portion is more primitive than in Helix ; the 
forms with one duct sac and multifid glands in two packets are the most 
highly differentiated forms ; Dutilleul. 
The function of the spiculum amoris as Gopulatory is indicated by the 
condition in certain species of Ariophanta and Tennentia described by 
Semper, where it is perforated ; the Vitrinidce seem to furnish an inter- 
mediate stage, which agrees well with the systematic position they occupy 
in the Pulmonula ; Simroth (4). 
In Vitrina elonc/ata , Drap., the spiculum amoris is composed of chitin 
or conchiolin, and has the form of a curved funnel leading put from a 
glaud ; hence it is not homologous with the analogous organ of Helix. 
This is compared with the state of things in other Vitrince ; the glandulm 
mucosae are described, and a classification based on these compared with 
one founded on the radula. The general anatomy of the genus being 
taken into consideration, the conclusion is drawn that the “ Vitrince are to 
be regarded as a divergent stem, perhaps connected at its root with the 
aulacognathous Hyalines , and lead on to the Limacidce by continued retro- 
grade metamorphosis”; Wiegmann. 
Copulation of Limax tenellus , with figs, of organs ; Simrotii (1), 
p. 2G. 
A detailed description is given of a case in which the generative 
apparatus of Helix pomatia was divided into three entirely separate 
groups ; no phylogenetic significance was attributed to the arrangement ; 
Bietrix. 
Hectocotylised arm of Tremoctopus gracilis , Eyd. & Soul., in early 
developmental stage described by Hoyle (1), p. 71. 
Sexual difference in shells of Unio, indicated by Sterki, p. 56. 
10. Embryology. 
Copulation was observed in captive specimens of Avion and Helix , but 
in the latter atrophy of the ova always took place. [1] Karyo/cinesis 
in the sperm-cells of Helix. — The spindle-fibres are really the persistent 
framework of the regular coil, the chromatin of which has been con- 
centrated at the equator, while the unstained ground-substance persists 
in toto. The microsomata seem not to be solid, but disposed on the 
framework of the coil like pearls on a string. The spindle is formed from 
the coil-framework by the concurrence of the individual segments of the 
latter in one point at the poles, thereby becoming more stretched, and 
entering into intimate connection with the protoplasmic masses. When 
division is slow the pole-plates can be seen to separate from the spindle- 
fibres and become regular nuclei ; the spindle fibres contract towards the. 
