432 NOTES AND MEMORANDA. 



have sliown to be necessary for the Spongitv, any further information 

 is obviously important. In two siliceous sponges and in a horny 

 sponge Eimer observed a number of canals, which enclosed a whitish 

 body, which contracted on irritation ; believing this to be part of the 

 sponge, and rejecting the idea of its being hydroid in character, Eiraer 

 proposed to call it the prehensile animal (Fangs- thier). Two English 

 observers, Mr. Carter and Professor Allman, have since 1872 

 observed similar cases, and they have both regarded the " Fangs- 

 thier " as a hydroid ; to this conclusion Schulze is also led. He 

 says that in no case that he has examined can he regard the 

 neraatocysts as forming an integral part of the sponge-body ; in all 

 cases they have been observed on the surface or in the canals which 

 are so characteristic of these lowly forms, and in all cases it has 

 been easy to demonstrate that they are intruders. The four sponges 

 examined belonged to the genera Beniera, Suherites, Esperia, and 

 Myxilla. As the characters of this form are found by Schulze to 

 correspond to the description given by Eimer, with the sole exception 

 of their structural continuity with the sponge, it does not seem 

 necessary to enter into fui-ther details ; the accounts of Carter and 

 Allman are stated to be too short to allow of any satisfactory 

 comparison. 



As to the development of this Spongicola, no information was 

 obtained ; but the author is of opinion that it belongs to the Hydroida 

 or Hydro-medusfe, although there are indications of a Scyphistoma 

 stage, such as is seen in the common Aurelia anrita, with which there 

 are certain other points of agreement in the histological and morpho- 

 logical details. 



Deep-sea Siphonophora. — Professor Studer's observations * are 

 reviewed in M. Lacaze-Duthiers' ' Archives.']" The author points 

 out that there are indications of a fauna intermediate between that 

 of the surface and that of " abyssal " depths : during the voyage of 

 the ' Gazelle,' Siphonophora were obtained, which can be satisfactorily 

 shown to have come from depths varying from 500 to 2000 fathoms 

 and from a region in which the temperature was from 2° to 6°. 

 Two new species of Rhizopjhijsa — R. conifera and It. inermis — are 

 described, as is also a new genus, Bathyphjsa ahyssorum (1880 

 fathoms). The author calculates that the air-sac acts in just the 

 same way as in those species that live near or on the surface. 



Histological Characters and Development of Myriothela. — Herr 



Korotneff, of Moscow, makes some brief observations \ on this subject, 

 the interest of which has been increased of late years by the work of 

 Professor Allman. Dividing the body into the three regions of foot, 

 median region, and upper region, he proceeds to point out how they 

 differ ; the walls of the body everywhere consist of ectoderm, support- 

 ing lamella, and endoderm. The ectoderm consists of several layers, in 

 which three distinct sets of cells may be made out. Below the superficial 

 layer there is a layer of subepithelial embryonic cells, in which the 



* ' Zeitschr. f. wiss. Zoo].,' xxxi. (1878) 1-24. 



t ' Arch. Zool. Expe'r. ct Gen.,' vii. (1878), Notes, xiii. 



X ' Zool. Aiizeigxr,' i. (1878) 363. 



