566 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the body. The first kind arises from the mucous cells, the secretion of 

 these single-celled glands being luminous. The points of intenser light 

 on the sides of the animal come from luminous organs formed by the 

 aggregation of single-celled glands. Each of these, even when associated 

 with others, retains its bottle-shape and its long separate duct. The 

 number of cells that go to make up a luminous organ may be as many 

 as twenty. The development of the organs can be traced step by step 

 in the same animal. Whether the secretion of the mucous cells is 

 luminous, alone or with the co-operation of that of the albumin cells, 

 was not demonstrated. But the luminosity of Phyllirhoe is undoubtedly 

 extra-cellular and extra-glandular. The animal is probably poisonous, 

 and the biological significance of the light may be analogous to that of 

 warning colours. 



Gastropod Foot and Branchial Cavity.* — Hilda M. Bishop has 

 studied the structural features of the foot of various Gastropods in 

 correlation with the observed functional activities, e.g. in Haliotis, 

 Patella, Trochus, Paludina, Littorina, and Cijprsea. The creeping 

 mechanism, the adhesion at rest, and the retraction into the shell, are 

 particularly discussed. There are also notes on the ctenidia and on the 

 mucus-glands in the branchial cavity of Littorina. 



New Genus of Nudibranchs.f — A. Vayssiere describes Eliotia 

 souleyeti g. et sp. n., a new type from the Mediterranean, which he names 

 after Charles Eliot and Souleyet. It is a minute form with its nearest 

 relatives in Madrella. A new family, Madrellidae, is proposed for the two 

 genera, and this is left in the meantime among the iEolididae adjacent to 

 the Coryphellidas. 



Tentacular Anomaly in Chromodoris elegans. % — A. Vayssiere 

 describes a specimen in which the left rhinophore or dorsal tentacle was 

 bifurcate at the base. The associated nerve showed a simple bifurcation 

 as it entered the stalk. 



8. Lamellibranchiata. 



History of Mya arenaria.§— Henry H. Howorth argues. that Mya 

 armaria, one of the very commonest shells in the present seas of 

 Scandinavia, Britain, and Belgium, has only recently invaded this area. 

 It is not an Arctic shell, but a boreal one. It has not been found living 

 in Arctic waters, and the statemeut that it occurs there has been due to 

 a mistaken inference. Hence, all deductions as to glacial climate 

 deduced from its having occurred in certain beds must fall to the ground. 



Marine Lamellibranchs of Siam.||— H. Lynge reports ou a large 

 collection from the Gulf of Siam, which raises the number of known 

 species from that region from 85 to 379, and includes many new forms. 

 There do not seem to be any peculiar forms, and the whole character of 

 the collection is Indo-Pacific. 



* Ann. Nat. Hist., v. (1910) pp. 513-24. 



t Ann. Sci. Nat., x. (1909) pp. 97-108 (2 pis.). 



% Tom. cit , pp. 109-10 (2 figs.). 



§ Proc, Zool. Soc. London, 1909, pt. 4 (published 1910) pp. 745-67 (8 figs.). 



II Mem. Acad. Sci. Danetnark. v. (1909) No. 3, pp. 100-299 (5 pis. and 1 map). 



