ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 983 



the Gephyreans projecting externally. The tube when first discovered 

 was quite empty, and the object of it was unexplained. Eecently, how- 

 ever, it has been found that the inhabitant of the cavity of the tube 

 in the substance of which the Phoronis grows is a large sea-anemone, 

 of the genus Cerianthus. The tube in which the anemone dwells is 

 not formed by it alone, but partly by the Phoronis, as is proved by 

 an examination of the texture of the tube. 



We have thus a very remarkable instance of mutual co-operation 

 in two animals belonging to widely diflferent classes. The advantage 

 derived by the Gephyreans from association with one of the Actinidae 

 is dependent on the power of the latter of killing small organisms by 

 its thread-cells, a plentiful supply of food being thus provided both 

 for the anemone itself and the colony of Phoronis, common enemies 

 being at the same time warded off. In return for this the Phoronis 

 helps to build and to strengthen the protecting case in which the 

 Cerianthus lives. 



Thompson's Bibliography of Protozoa, Sponges, Ccelenterata, 

 Worms, and Molluscoida.* — Cams and Engelmann's ' Bibliotheca 

 Zoologica ' ends with the year 1860, since which time no attempt has 

 been made to provide a list of the books and papers on Invertebrates, 

 and workers have been obliged to search through the yearly volumes 

 of the ' Zoological Eecord.' Prof. D' Arcy W. Thompson has therefore 

 collected the titles of the books and papers published from 1861 to 

 the end of 1883, relating to the above classes of Invertebrates. 

 The book will be very useful to naturalists, and it is to be regretted 

 that there appears to be no prospect of extending it to the remain- 

 ing classes or to Vertebrates. 



Mollusca. 



Fecundation in Cephalopoda.f — M. L. Vialleton has observed 

 that in the female Sepia the spermatophores are not identical with 

 those that are found in the male, but have the form of elongated flasks, 

 the contents of which escape by the open necks ; they are chiefly to 

 be found in the ventral half of the buccal membrane, and especially 

 near the two ventral lobes. A little below the top of each of these 

 there is a pit, which is the opening of an elongated gland, formed by 

 a longitudinal canal round which are inserted acini, filled with a 

 whitish fluid. This fluid is composed of spermatozoa in a colourless 

 fluid. The glands are to be regarded as copulatory pouches. 



In Lolifjo subulata the author has been able to observe the 

 spermatozoa being guided by the folds of mucous membrane and 

 making their own way into the pouch ; in L. vulgaris, females have 

 been often seen, after having expelled their ova by the funnel, to 

 retain them between their two ventral arms in front of the mouth, and 

 it is possible that they then voluntarily fertilize them with the 



• Thompson, D'A. W., ' A Bibliography of Protozoa, Sponges, Coelenterata, 

 anf] Worms, including also the Polyzoa, Bruchiopoda, and Tunicata, for the years 

 18*51-83,' viii. and 284 pp., 8vo, Cambridge, 1885. 



t Comptes RtndiiB, ci. (ISS.'i) pp. 619-21. 



H 8 2 



