770 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
cerebro-pleural commissures. The general scheme of classification 
suggested is as follows : — 
Group Taenioglossm. 
I. Sub-group. Architaenioglossae (allied to Rhipidoglossae). 
1. Fam. Cyclophoridae. 2. Paludinidas. 3. Cypraea3. 
II. Sub-group. Neotaenioglossae. 
1. Subdivision. 2. Subdivision. 
N. brevicommissurata. N. longicommissurata. 
1. Littorinidas (allied to Bythinia). 1. Tritonidee. 
2. Neurobranchia. 
3. Yalvatidae. 
4. Ampullaridae. 
5. Melanidae. 
6. Cerithidae. 
7. Pyramidellidas. 
8. Turritellidae. 
9. Yermetidae. 
10. Entoconchae. 
11. Onustidae. 
12. Naticidae (Operculata, Natica ; Anoperculata, Sigarelus and Mar- 
seniadse. 
13. Calyptraeidas, including in serial order Galerus, Trochita , Crucibu - 
lum, Crepidula, Ergsea, Janacus. 
14. Cyclomyaria (Capulidae and Hipponicidae). 
Anatomy of Siphonaria.* — Dr. B. Haller finds that Siphonaria gigas 
Less, is not a Pulmonate, but an Opisthobranch modified in adaptation 
to life among the rocks, with its nearest relative in Umbrella. It is a 
very old form of Pleurobranch, with many primitive characteristics : — 
the state of the nervous system, the double kidneys, the simple gonads, 
the row of gills and the double branchial veins. It is divergent in 
adaptation to a special habitat, and may be taken as type of a distinct 
family of Tectibranchiata which the author designates Semicyclobranchs. 
Alleged Anal Eye of Larval Opisthobranchs.f — Dr. G. Mazzarelli 
discusses the organ which Lacaze-Duthiers and Pruvot described in 
1887 as an anal larval eye. It had been previously described by several 
zoologists, most of whom had regarded it as glandular. Langerhans 
and Pay Lankester had interpreted it as a kidney, Trinchese as an anal 
gland, and so on. Lacaze-Duthiers and Pruvot regarded it as ectodermic, 
Trinchese as mesodermic, Lankester as endodermic. The organ in 
question is a pyriform vesicle containing pigment. Its anatomical 
occurrence, its included concretions, its development show that it is not 
an eye, but certainly a kidney. Thus all the dilated portion and part 
of the neck is n esodermic ; only the distal end of the neck is ectodermic. 
“ The alleged ‘ anal eye ’ of larval Opisthobranchs is in point of fact 
the permanent kidney.” 
* Arbeit Zool. Inst. Univ. Wien (Claus), x. (1892) pp. 71-100 (3 pis.). 
t Atti (Rend) R. Accad. Lincei (1892) pp. 103-8. 
2. Dolidae. 
3. Strombidae. 
4. Pteroceridae. 
