Fkuiiuaey 10, 18S3. 1 



SCIENCE. 



51 



buds may develop into a parent stock, while the ori- 

 ginal jiarent becomes separated, as a bud, from the 

 body of its own offspring. He has also verified 

 Trembly's discovery that Hydra sometimes multi- 

 plies by tran verse fission. He has rediscovered the 

 so-called anux, which was described by Folkes in 1742, 

 and by other observers of _the last century. It is in 

 no sense an anus, but simply the remnant of the 

 channel of communication between the digestive cav- 

 ity of the bud and that of the pai-ent. 



Baker's discovery, in 1744, that the two tentacles 

 which first appear in the bud lie in the plane which 

 passes through the axis of the body of the mother, 

 has recently been verified by Mereschkowsky. Mar- 

 shall not only finds that this is the case, but that the 

 reproductive organs appear in the same plane. He 

 also finds that when the tentacles of a full-grown 

 specimen are cut off, the two which are first re-devel- 

 oijed lie in this same plane. He therefore concludes 

 that Hydra is in a certain sense, a bilateral animal. 



His attempts to repeat Trembly's experiment of 

 reversing a Hydra, failed completely, like those made 

 by Baker and others; but a Japanese naturalist, Prof. 

 Mitsukuri, has recently been more successful, and 

 has verified Trembly's statement. 



Marshall concludes that Hydra is, in a certain 

 sense, both a liydroid polyp and a Scyphostoma. — 

 {Zeitschr. wiss. zooL, xxxvii. 664.) w. K. B. [143 



Anatomy and histology of Cyanea. — Dr. Lin- 

 denfeld gives a minute and profusely illustrated ac- 

 count of the general anatomy and the histology of 

 a new species of Cyanea (C. Annaskala) from south- 

 ern Australia. The paper is Part I. of a monograph 

 on -the Coelenterata of the South Sea. — (Zeitschr. 

 wiss. zool., xxxvii. 465.) w. K. B. [144 



MollTisks, 

 The organ of Bojauus of the oyster. — Mr. P. 



P. C. Hoek, of the zoological society of the Nether- 

 lands, has recently published his investigations upon 

 the generative organs and the organ of Bojanus of 

 Ostrea edulis L., as observed by him at the zoologi- 

 cal station of the society in Bergen-op-Zoom on the 

 Escaut. He finds it to open into tiie pericardiac cavity, 

 and also communicates with the generative openings 

 on either side. Its principal cavity is a wide canal 

 clothed with epithelial cells bearing very long cilia, 

 communicating with numerous surrounding smaller 

 cavities formed by induplicaturesof membrane. This 

 is believed to be its glandular portion. It lies close 

 against the ventral side of the adductor, and extends 

 into the substance of the mantle laterally. — [Comptes 

 rendas, Nov. 2, 1882.) 



The present writer, in the course of his investiga- 

 tions into the anatomy of O. virginica Gmel., has 

 found a somewhat similar paired organ below the 

 great double adductor. On either side it is partially 

 embedded in the mantle; crescent-shaped, as seen 

 from the side; frequently marked by brownish tissue 

 in its walls ; about five-eighths to three-fourths of an 

 inch long, and a sixteenth to an eighth of an inch in 

 width at its widest portion. In sections through this 

 organ and the adjacent tissues of hardened specimens, 

 the following details are revealed : A number of large 

 central canals, clothed internally with epithelium bear- 

 ing very long cilia, and communicating with smaller 

 tubular cavities of irregular form, or with somewhat 

 folded walls, lined with epitlielium bearing shorter 

 cilia. The inner non-glandular part embraced the 

 parieto-splanchnic ganglia, sections of which appear 

 in some of the preparations. The connection of the 

 organ with the generative openings and pericardiac 

 cavity was not traced. There can be little doubt but 



that what M. Hoek and myself have seen is really the 

 renal organ of these animals. — J. A. E. [145 



A remarkable molluscan type. — An interest- 

 ing discovery has been made during a study by Mr. 

 Dall of the deep-sea mollusks dredged off the Antilles 

 by the U. S. coast-survey steamer ' Blake,' under 

 the supervision of Prof. A. Agassiz. A living spe- 

 cies of the genus Dimya Rouaultis found attached 

 to the margin of dead shells. This genus is fossil in 

 the eocene of the Bos d'Arros, France, a deposit 

 equivalent to that of the Paris basin. The type and 

 sole recognized species until now was first figured by 

 D'Arcliiac as an Anomia; and, in the same year, its 

 true characters were recognized by Eouault. Since 

 then the genus has attracted little attention, being 

 barely mentioned in general treatises. It is traceable 

 continuously through the formations on the Mediter- 

 ranean, from the eocene to the pliocene ; Ostrea 

 tenuiplicata of Seguenza turning out to be a Dimya, 

 closely allied to the original type of Rouault, to 

 which, however, the recent form from the Antilles 

 is still more similar, — indeed, j^ractically identical. 

 The interest of the discovery does not, however, lie 

 chiefly in its ancient lineage, but rather in the re- 

 markable characters of Dimya. It is practically an 

 oyster, with two adductor muscles, and a pearly out- 

 side to its shell. It combines in itself features sup- 

 posed to be characteristic of different orders of 

 mollusks, and many separate groups within those 

 supposed orders. "The outer layers have a silvery 

 nacre as in some oysters, like which Dimya has a 

 porcellanous inner layer. The hinge has a pit like 

 Hinnites or some pectens, roughened in one species 

 as in Pseudamussium Verrilli. The branchiae are of 

 a very primitive type, consisting of long disunited 

 filaments attached to a cord-lilce l)and, forming a liv- 

 ing fringe. Other aud still more peculiar features 

 require more study. It would seem as if the definite 

 establi^hmeat of this genus gave the coup-de-yr&ce 

 to the old order Monomyaria. — w. H. v. [146 



Worms. 

 Structure and development of Dinophilus (a 

 turbellariau). — Dinophilus is a marine rhabdocoe- 

 lous planarian, resembling externally an annelid 

 larva. A new species (D. apatris) was found in 

 the marine aquarium of the zoological institute at 

 Freiburg-im-Breisgau, and forms tlie subject of a 

 valuable paper by Dr. Korschelt. The female is 

 some thirty times larger than the male; is developed 

 from large eggs, while the male is developed from a 

 small egg. The structure of the female is described 

 in considerable detail, especially as regards the his- 

 tology. The most characteristic features of the 

 female are the two bunches of setae on the front of 

 the head, the constriction forming a neck, the five 

 rings of cilia around the body, and the proboscis. 

 This last is a solid mass attached to the base of a 

 hollow sheath underneath the pharynx ; when re- 

 tracted the posterior end is bent upwards like tlie leg 

 of an L. The sheath opens just inside the mouth. 

 The proboscis is composed mainly of striated circu- 

 lar muscles, inside of which are longitudinal muscles. 

 The, tip is specially differentiated. The probosics 

 can be thrust out and withdrawn with great rapidity, 

 and ijrobably serves to gather diatoms, etc., on which 

 the animal feeds. It will be remembered that an 

 organ similar in some respects exists in Prostomum, 

 but cannot be regarded as homologous, for it lies 

 above and not below the mouth. The male is not 

 only smaller than the othei- sex, but shows a rudi- 

 mentary organizalicm; was observed to live ten days 

 only, while the females were kept alive for months. 



