50 SUMMARY OF CUEEENT RESEARCHES RELATING TO 



4 ft., except the third one on the right, which is 2 ft. 11 in., and is 

 hectocotylized. 



As a sexual character he calls attention to the gradual decrease 

 in size of the suckers in passing from the proximal to the distal end 

 of the arm in the male ; whilst in the female the suckers soon become 

 indistinct, and are replaced by closely-set tubercles. In a male there 

 were 300 suckers on one arm, and only 100 in a corresponding arm 

 of a female of the same size. 



Post-oral Band of Cilia in Gasteropod Velig^ers.*— Dr. J. P. 

 McMurrich draws attention to a post-oral band of cilia, in addition to 

 the pre -oral band, in larvre of Crepidula fornicata, Fulgur carica, 

 Neptunea, Montaguia, and others. Between these two bands are 

 numerous cilia, continuous with those lining the mouth, as in 

 Polygordius. 



The following phylogenetic history is suggested for the Gastropods ; 

 the ancestor of these and of other annelids was a " Trochophore," which 

 in the former developed the (larval) shell : the presence of this ren- 

 dered the pre-oral cilia insufficient, and hence the formation of the 

 velum ; the presence of the shell may be connected with the absence 

 of metameric segmentation. 



Development of Pissurella.j — M. L. Bontan comes to the con- 

 clusion that Fissurella by its development, shows itself to be a true 

 Gastropod, and not to be allied to the worms; it has a persistent 

 larval shell, its larvse are emarginuliform, and rimuliform, before 

 reaching the adult condition ; the apparent symmetry of the adult is 

 really an asymmetry which gradually becomes marked. 



Limacidae of Saint-Vaast-la-Hougue.| — M. S. Jourdain contends 

 that malacologists have divided too finely the species of Limacidae. 

 Instead of basing their diagnoses on the general form, coloration, 

 structure of the shell, and conformation of the jaws, characters which 

 vary with age and habitat, they ought to have recourse to the internal 

 organs, and especially to the arrangement of the generative apparatus. 

 The pedal gland is also of service ; it contains a cylindrical excretory 

 canal which extends more or less along the median line, and receives 

 the mucoso-glandular secretions of the lobules of a racemose gland 

 on either side of it ; the internal face of the canal is vibratile. In 

 the Limacidge it arises as an invagination of the ectoderm, and 

 subsequently becomes branched ; the extremities of the branches 

 are invested by mesodermic cells which rapidly become secretory. 

 M. Jourdain limits the number of species found in the environs of 

 Saint- Vaast-la-Hougue to five — Avion rufus, Limax agrestis, L. 

 maximus, L. variegatus, and Milax gagates ; and he gives diagnoses 

 of these, limiting himself, however, here to the characters which have 

 been especially neglected by malacologists. 



Spermatogenesis in Pulmonata.§ — Herr G. Platner describes the 

 spermatogenesis in Arion and Helix, and reviews the relative researches 



* Johns-Hopkins Univ. Circ, v. (1885) pp. 5-6. 



t Comptes E.-ndus, ci. (1885) pp. 710-2. J Ibid., pp. 963-6. 



§ Arch. f. Mikr. Anat., xxv. (1885) pp. 5G4-581. 



