986 SUMMARY OF CURRENT RESEARCHES RELATING TO 



mentary canal, and reaching up to the level of the oesophagus. The 

 male organs exhibit the same plan. 



(d) The ova are small and black, issuing at the anterior end of the 

 branchial cavity, and deposited (in Fiss. reticulata at least) by aid of 

 tmdulatory movements of the foot, in a single layer on flat stones, &c., 

 to which the enveloping glairy substance causes them to adhere. 

 There is no copulation, the spermatozoa issue in whitish jets from 

 the apical aperture, and the ova are fertilized after they are laid. An 

 account of their development is reserved. 



Respiration of Truncatella.*— In order to settle the disputed 

 question of the mode of respiration in this minute mollusc, M. A. 

 Vayssiere examined a number of specimens of Truncatella truncatula, 

 and discovered a distinct gill with twelve to fifteen triangular ciliated 

 lamellae, lying attached to the roof of a dorsal respiratory cavity. 

 The gill lies transversely to the longitudinal body-axis, the lamellae 

 admit of separate movement, and as the water stored within the 

 respiratory sac can only evaporate slightly in the moist environment 

 of Truncatella, the animal may remain for a considerable time without 

 renewing its supply. M. Vayssiere has also investigated the complete 

 anatomy of this mollusc, of which the largest specimens hardly attain 

 the size of 4 mm., but his research has not discovered any notable 

 peculiarity of organization. 



Spawning of Fulgur perversus.f — Mr. J. Willcox describes the 

 spawning of Fulgur perversus, which takes place in the month of 

 March. When the mollusc is about to spawn, it first descends into 

 the sand deeply, and attaches the egg-case to a bivalve shell. As the 

 process of extrusion permits, it ascends until its siphon reaches the 

 surface of the sand. In this position it remains until the spawning is 

 complete. During the process of formation the egg-case is forced 

 upward, appearing in the form of a loop above the sand, though no 

 portion of the parent is then visible. When completed, one end of 

 the string of egg-cases floats freely in the water. As only four or five 

 of the egg-cells are found in the body of the parent at one time, in 

 the process of formation, it is presumed that the whole series of cases 

 requires a long time in its development. 



Glycogen in " Vesicular Cells " of Molluscs 4— One of the results 

 of Mr. E. E. Blundstone's investigation of the connective-tissue and 

 vascular system of Mollusca is the demonstration of glycogen in those 

 cells of the connective tissue which Lankester described as "vesicular." 

 The connective tissue is either composed of irregular cells joined by 

 the tips of their processes, or of still more irregular cells formed into 

 lamellee by being imbedded in a thin film of intercellular ectoplasm, 

 from which, however, some (" vesicular ") cells of enormous size 

 project into the blood. In these cells as obtained from the simplest 

 regions of the mantle oi Anodon, or as readily observed by -spreading 

 out the " mesentery " of Helix, glycogen was not only extracted, but 



* Comptes Rendus, ci. (1885) pp. 575-7. 



t Proe. Acad. Nat. Sci. Pbilad., 1885, pp. 119-20. 



J Proe. Koy. Sue, xxxviii. (1885) pp. 442-5. 



