ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 1001 



and in a few cases the shell was completely empty. In the interioi' 

 of the blisters were found one or more specimens of a very small 

 Annelid, by which the mischief had been efltected — Pohjdora ciliata. 

 One specimen of a second species was also obtained, P. liolyhranchia 

 n. sp. which the author describes. 



Anatomy and Histology of Aulophorus vagus.* — Mr. J. Eeighard 

 gives an account of the structure of this American worm, the first 

 description of which we owe to Prof. Leidy ; the animals are either 

 found single, or comjjosed of two to four zooids joined by " bud-zones " ; 

 no other mode of reproduction than that by budding has yet been 

 observed. 



Unicellular dermal glands are found in the region of the head, and 

 the other dermal appendages are stylets, bristles, hairs, and cilia ; the 

 muscular system consists of layers of annular and longitudinal fibres, 

 together with special muscles for moving the bristles, the pharynx, 

 and the supra-oesophageal ganglia. The pharynx is described as 

 forming a highly specialized organ, used both for seizing the food 

 and in locomotion, and also as a sucking-disc ; in the oesophagus the 

 cilia are so long as almost to fill its lumen. The "liver-cells" are 

 lens-shaped and have a large nucleus ; they contain numerous golden- 

 brown drops in a part of the intestine. 



The vascular system consists of a dorsal and ventral vessel, united 

 by a plexus in the head, and one in the region of the pavilion, and by 

 numerous vessels surrounding the alimentary canal. The dorsal 

 vessel is contracted, as are the lateral branches, in the eighth, ninth, 

 and tenth segments ; when one of these vessels is distended its walls 

 are seen to contain large, prominent nuclei, evidently belonging to 

 the muscular elements ; when contracted the walls of the vessels show 

 longitudinal and transverse striae. Respiration is principally effected 

 by the pavilion, or jjosterior expansion, which is thickly covered with 

 cilia, and contains numerous muscular elements ; its digitiform 

 appendages are hollow, and their cavities are continuous with the 

 coelom ; as the walls of the intestine are richly covered by a network 

 of blood-vessels, and bathed by a strong stream of water, they are 

 doubtless also respiratory in function. The ventral nerve-cord has on 

 its upper surface three giant fibres ; these are, for most of their course, 

 simple, empty tubes. The author was unable to trace a connection 

 between the lateral lines and the oesophageal commissures, as has 

 been done by Semper for Nais. 



As in various other parts of its organization, so, too, in its 

 segmental organs Aulophorus recalls the description of Dero obtusa as 

 given by Prof. Perrier. It is possible that the cells covering \)avi of 

 the walls of the nephiudial tubes form the basis of the tubes in which 

 the animal lives ; but it is to bo borne in mind that similar cells are 

 found in forms that are not tube-formers. 



Angiostomum.f — Dr. 0. von Linstow gives an account of the 

 species of the genus Anfjiostomum, which appears to stand midway 



♦ Proc. Amer. Acad., xx. (1885) pp. 88-106 (3 pis.), 

 t Arch, f. NaUirg08(;h., li. (1885) pp. 1-13 (2 pis.). 



