CORONAT.E — PERICOLPA, I'KIUIMI VI.LA . 543 



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

 appears to be immature, beinp; only 20 mm. hij^h and 16 mm. wide. Found off the south coast 

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



Genus PERIPHYLLA Steenstrup, 1837. 



P<rr;'/>/)y//a,STEKNSTRi'p, 1837, Acta ct Cat. Mus. Hafniensis.— Haf.ckf.l, iSSo.Syst.dcr Medusen, p. 418; j8Si, Deep-sea Medusa: 

 Challenger Report, Zool., vol. 4, p. 63.— Claus, 1886, Arbeit. Zool. Inst. Univ. Wien, Bd. 7, p. 99.— Vanhokfkn, i89Z, 

 Ergeb. dcr Plankton Exped., Bd. z, K. d., pp. 4, 6, ji.— von Lendenfkld, 1884, Proc. Linncan Soc. New South Wales, 

 vol. 9, p. 168.— Maas, 1897, Mem. Mus. Comp. Zool. at Harvard College, vol. 23, No. 1, pp. 28-64; '9°4' Result. Camp. 

 Sci. Prince de Monaco, fasc. 28, p. 44; 1903, Scyphomedusen der Sihoga Expedition, Monog. 1 1, p. 5; 1907, Ergeb. Fort- 

 schritte dcr Zool., Bd. I, pp. 199, 219, etc. — Vanhoffen, 1902, Wissen. Ergeb. dcutsch. Tiefsee Expedition, Dampfer 

 I'aldh-ia, Bd. 3, Lfg. I, p. 21; 1906, Nordisches Plankton, Nr. 11, p. 41. — Bigelqw, H.B., 1939, Mem. Mus. Comp. Zuol. 

 at Har\'ard College, vol. 37, p. 24. 



Periphema, Haeckel, 1881, Deep-sea Medusa: ChaUenger Exped., p. 84. 



GENERIC CHARACTERS. 



Periphyllid;e with 4. interradial rhopalia, 12 tentacles, 4 perradial and 8 adiadial. 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 

 pits m the floor ot 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 mto 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 

 betore 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 rhopalia 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 Vanhiiffen, 1902, and Maas, 1904, recognize but 3 species as follows: 



P. h\acinthina with high, narrow bell, its height being to width as 44 to 23. The lappet pouches are dark-brown, so that 



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

 P. dodeeahostrycha 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 "mirabilh," Haeckel, appears to be identical with P. regina; and P. ^^humilis" Fewkes, appears to be an 



imperfect P. dodeeahostrycha. P. peronil, H!iecke\= Charybdea periphylla, Peron et Lesueur, 1809, p. 332, is too 



imperfectly known to be classified. 



I think it probable that there is but a single species o( Periphylla {P. hyncinthina), and 

 that P. dodeeahostrycha and P. regina 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 subject to constant changes due to growth or to state of 

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

 that P. hyacinthina and P. dodeeahostrycha are identical. 



Peripalina corona of Haeckel , 1880 fSitzungsber. Jena. Gesell. fiir Med. und Natunv. 

 Jahrg. 1880, Feb. 20; Syst. der Medusen. p. 418), is probably 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 taeniolae of the basal stomach are solid ligaments 

 without gastral filaments. 



