768 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Commensalism between a Gymnoblastic Anthomedusoid and a 
Scorpaenoid Fish.* — Dr. A. Alcock finds that a fixed Hydroid (a species 
of Stylactis ) and a highly locomotive animal (a fish of the genus Minous) 
have symbiotic relations. Never is either found without the other ; 
if two species of the genus occur together the polyp selects M. inermis. 
The polyp (which is called S. mmol') gets the advantage of change of 
place, the fish has its appearance disguised. 
B. INVERTEBRATA. 
Mollusca. 
y. Gastropoda. 
Genital Apparatus of Helix, j — Dr. H, von Jkering devotes a lengthy 
memoir to the morphology and systematic value of the generative ap- 
paratus of Helix. He commences by reminding us that 3400 forms 
were enumerated by Pfeiffer in 1877, and that the various schemes that 
have been proposed for breaking up this huge group into smaller 
sections have been far from successful. He is himself convinced that 
a key is to be found in the genital system. He recognizes in the family 
Helicidae seven well-marked genera which he arranges phylogenetically 
thus : — 
Dofcasia 
With this statement we must content ourselves, as we must devote the 
space at our disposal to the author’s speculations as to the phylogeny of 
the Nephropneusta. He thinks it so clear that the order Pulmonata 
is a zoological error that it is unnecessary to enter on a discussion 
of the question. The Branchiopneusta form an independent group 
* Ann. and Mag. Nat. Hist., x. (1892) pp. 207-14 (1 fig.), 
t Zeitschr. f. Wiss. JZool., xlv. (1892) pp. 386-520 (2 pis.) 
