NOTES AND MEMORANDA. ' 431 



After tracing tlie history of the ScypMstoma and EpJiyra stages, Claus 

 concludes with observing that there is no fundamental difference l)et\veen 

 the Mednsce and the Pohjijs ; the Scyphistoma is a polypoid Medusa, 

 and the Medusa a broad, discoid, flattened Polyp, which has ceased to 

 be fixed, and has become adapted to locomotive habits by the aid of 

 its swimming bladder ; the " grappling lines " are the marginal 

 tentacles ; the radial pouches of the gastro-vascular system are 

 represented by the radial vessels, while the gelatinous disk forms a 

 very strong mesodermal layer, which develops into a supj)orting 

 lamella in the Uydroida, and a skeleton in the AntJiozoa. 



The rays along which are set the genital pouches (and marginal 

 bodies) are rcgarried as rays of the second order, which are developed 

 at an angle of 45^ to the four primary tentacles, or rays of the first 

 order ; while the name of intermediate rays is given to the eight rays 

 of the Ephyra form in which the tentacular vessels are developed. 



Aca/ephce and Hydro-medusce. — In the opinion of Professor Claus, 

 the differences between these forms have never been satisfactorily 

 stated ; the names Cryjjtocarpce and Phanerocarpce, or Gymnoplithal- 

 mata and Stegannphthalmata, or Craspedota and Acraspoda, which we 

 owe to Eschholtz, Forbes, and Gegenbaur, are insufficient, for the 

 large and complicated marginal bodies of the Acalephce correspond, 

 from a morphological point of view, to tentacles ; the cavities in the 

 substance of the umbrella in which the generative organs of the 

 Cryptocarpce are placed, are foimd to be present in a number of 

 the Phanerocarpce ; neither in structure nor in position is there any 

 fundamental difference between them. A more valuable point of 

 difference is to be seen in the presence or absence of the filaments 

 which appear to form tentacular appendages to the generative organs ; 

 the Steganoplitlialmata {Piscomedusce) are stated to be Scyphistoma 

 Med usee with filaments, while the GymnopjMlialmata are Hydroid 

 Medusce without filaments. With these considerations in mind, Claus 

 has lately addressed himself to the examination of the characters of 

 the Charyhdeidce and ^ginidce, w'hich had been placed by Fritz 

 Miiller with the Hydro-medusce, and by Agassiz among the Acaleplice 

 (Piscophora). The great similarity in the external form of the bell 

 and of the manubrium in Charybdea and Oceania, as well as the pre- 

 sence in both of four primary rays, have been used as arguments for 

 uniting these forms ; but the number of the radial canals, marginal 

 bodies, and tentacles vary very greatly in the latter, and it appears to be 

 allied to the Hydro-medusce, while Charybdea presents distinct points 

 of resemblance to the Acalephce ; judged by the point on which Claus 

 insists, the Oceanidce are found to want the gastric filaments. 



Spongicola fistularis, a Hydroid inhabiting Sponges. —A 

 resume is given in M. Lacaze-Duthiers' ' Archives,'* of the observations 

 of F. E. Schulze on the above-mentioned form, the chief interest of 

 which is that it bears on the assertions of Eimer that the Spongice 

 are provided with nematocysts ; bearing in mind the changes in the 

 zoological scale which the researches, chiefly of Professor Haeckel, 



* ' Arch. Zo:il. Exper. et Gen.,' vii. (1878), Notes, ix. 



