CORONAT.E PERICOLPA, PUdl'll VLLA. 543 



ends approach one another closely. The medusa is very briefly mentioned by Haeckel and 

 appears to be immature, being only 20 mm. high and 16 mm. wide. Found off the south coast 

 of Australia. Described by Haeckel from a single preserved specimen. 



Genus PERIPHYLLA Steenstrup, 1837. 



Ptrifkylla,Situimtuf, 1837, Actaet Cat. Mus. Haf mends. HAECKEL, i88o,Syst.derMedugen,p.4i8; 1881, Deep-sea Medusa? 

 Challenger Report, Zool., vol. 4, p. 63. CLAIS, 1886, Arbeit. Zool. lust. 1'niv. \Vien, Bd. 7, p. 99. YANH'^KIN, 1892, 

 Ergeb. Jer Plankton Exped., Bd. 2, K. d., pp. 4, 6, 21. VON I.IMNI KLD, 1884, Proc. Linnran Soc. New South Wales, 

 vol. 9, p. 1 68. MAAS, 1897, Mem. Mus. Comp. Zool. at Harvard College, \ >!.:;, No. i, pp. 28-64; '94' Result. Camp. 

 Sci. Prince dc Monaco, fasc. 28, p. 44; 1903, Scyphornedusen drr Siboga Expedition, Monog. 1 1, p. 5; 1907, Ergeb. Fort- 

 schritte Jcr Zool., Bd. i, pp. 199, 219, etc. VANHU'K FEN, 1902, Wissen. Ergeb. deutsch. Tiefs.ee Expedition, Dampfer 

 I'uldivia, Bd. 3, Lfg. i, p. 21; 1906, Nordisches Plankton, Nr. ii,p.4i. BIGELOW, H. B., 1909, Mem. Mus. Comp. Zool. 

 at Harvard College, vol. 37, p. ^4. 



Periplifma, HAECKEL, 1881, Deep-sea Mcdus;c Challenger Exped., p. 84. 



GENERIC CHARACTERS. 



PeriphyllidaE with 4 interradial rhopaha, 12 tentacles, 4 perradial and 8 adradial. 16 

 marginal lappets grouped into 4 pairs of rhopalar and 4 pairs of tentacular lappets. A deep 

 annular furrow separates the dome-like apex of the exumbrella from marginal zone of bell. 

 Between this ring-furrow and the lappets is a zone of 16 pedalia, 12 in the tentacular and 4 in 

 the rhopalar radii, and these are separated one from another by 16 deep, radiating clefts, 

 which extend down the mid-axial lines of the lappets. There are 4 deep, interradial subgenital 

 pus in the floor of the subumbrella, lined along their edges by rows of internal gastric cirri. 

 The large central stomach extends peripherally outward into the subumbrella in the 4 perradii. 

 These 4 openings lead into a wide ring-sinus in the subumbrella which in turn sends out a 

 radiating vessel in the radius of each tentacle and rhopalium, 16 in all. These vessels fork 

 before reaching the tentacles or rhopalia, and their diverging ends curve around the edges of 

 the lappets and form a marginal ring-canal. 



The 4 interradial septa are bordered by lines of gastric cirri and there are 8 U-shaped 

 adradial gonads, one on either side of each septum. The tree ends of each gonad are directed 

 inward toward the stomach, and their convexities point outward toward the bell-margin. 

 The rhopaha have no ocelli, but contain a proximal mass of entodermal pigment and a distal 

 concretion. 



The medusae of Periphylla are deep-sea forms of very wide distribution. The so-called 

 species are not well separated, being based on the relative height and width of the bell and 

 on slight color distinctions. The bell appears to become relatively flatter as growth proceeds, 

 and therefore its proportions would seem to afford a poor criterion for specific distinctions. 

 Both Vanhoffen, 1902, and Maas, 1904, recognize but 3 species as follows: 



P. hyacinthina ^ith IML;!), narrow bell, its height being to width as 44 to 23. Tin- l.ipprt pouches are dark-brown, so that 



the gonads can not be seen through them from the outside. 

 P. dodtcaboslrytha with bell flat, bluntly pointed, its height being to width as 27 to 18. Gonads visible through the lappets 



from the outside. 



P. regina with dome-like rounded bell and light red-brown color. 

 Periphylla "mirabilis," Haeckel, appears to be identical with P. regina; and P. "humilis," Fcwkcs, appears to be an 



imperfect P. doJtcabottrycha* P. peronii, Haeckel = Charybdea perifil:\llii, Peron et Lesueur, 1809, p. 332, is too 



imperfectly known to be classified. 



I think it probable that there is but a single species of Periphylla (P. hyacinthina), and 

 that P. dodecabostrycha and P. n-gina are only varieties or local races. It is impracticable 

 to attempt to separate species upon slight differences of form or proportions in their bells 

 especially when such characters are sub]ect to constant changes due to growth or to state of 

 contraction. Bigelow, 1909, who has studied many specimens of these medusx, concludes 

 that P. hyacinthina and P. dodecabostrycha are identical. 



Penpalma corona of Haeckel , 1880 (Sitzungsber. Jena. Gesell. fiir Med. und Naturw. 

 Jahrg. 1880, Feb. 20; Syst. der Medusen, p. 418), is probablv a young Periphylla. Haeckel 

 states that the genus is characterized by the absence of interradial pits or perradial concavities 

 in the subumbrella, and that the 4 interradial taeniolz of the basal stomach are solid ligaments 

 without gastral filaments. 



