120 MEDUS.E OF THE WOULD. 



their shafts are of about uniform width throughout, the outer ends being very blunt, not taper- 

 ing. There are no other tentacles or marginal appendages. The 4 radial-canals and the ring- 

 canal are simple, narrow, and straight-edged; without glandular diverticula. 



The stomach is wide and barrel-shaped to cylindrical and is about three-fourths as long 

 as the depth of the bell-cavity. There is no peduncle and the 4 radial-canals run directly into 

 the stomach without enlarging as they approach its base. The mouth is well developed, but 

 the lips are simple, without the foldings commonly seen in other Tiarinae. 



The gonad is developed as an open network of more or less transverse folds over the ecto- 

 dermal wall of the stomach, excepting only the neighborhood of the mouth. The gonad is not 

 distinctly separated into 4 interradial parts, but is more or less fused over the perradial lines, 

 thus encircling the stomach very much as in medusae of the Codonidae or in Pandca con i en. 



The entoderm is yellow, the gonads being deep in color and the tentacles lighter. Other 

 parts are transparent. 



Found by the Prince of Monaco at Bear Island, between Norway and Spitsbergen, in 

 July, 1898. It is well figured and described by Maas, 1904. Hartlaub, 1907, considers this 

 medusa to be identical with Sarsia flammea Hartlaub. The general proportions of the two 

 medusae appear to be much alike, but the details of structure of the gonads and the color of 

 P. maasi appear to distinguish it from other medusae. 



Genus TURRIS Lesson, 1843, sens, amend. 



Turr'n+Tiara (in part), LESSON, 1837, Prodrom. Monog. Meduses, Nos. 17, 20 (not published); 1843, Hist. Zooph. Acal., 



pp. 283, 286. 



Turris + Oceania (in part), FORBES, 1848, British Naked-eyed Medusae, pp. 21, 26. 

 Turrh+ Tiara, AGASSIZ, L., 1862, Cont. Nat. Hist. U. S., vol. 4, pp. 346, 347. HARTLAUB, 1892, Nachricht. kgl. Gescll. 



Wissenschaft. Univ. Gottingen, pp. 20, 22. 

 Turris, AGASSIZ, A., 1865, North Amer. Acal., p. 164. 



Tiara+ Turris+ Catablema, HAECKEL, 1879, Syst. der Medusen, pp. 56, 60, 62. 

 Turris, FEWKES, 1881, Bull. Mus. Comp. Zoo], at Harvard College, vol. 8, p. 147. 

 Tiara, WAGNER, 1885, Wirbellosen des Weissen Meeres, p. 78. MAAS, 1905, Craspedoten Medusen der Siboqa Expedition, 



Monoe. 10, p. 14. BOVERI, 1890, Jena. Zeit. Naturw., Bd. 24, p. 339. (The egg gives rise to 2 polar globules.) 

 Cu1ablema-\- Turris + Tiara, VANHOFFEN, 1891, Zool. Anzeiger, Bd. 14, p. 444. 

 Catablema+ Tiara+ Turris, MAAS, 1904, Result. Camp. Sci. Prince de Monaco, fasc. 28, pp. 12, 15, 16. 



GENERIC CHARACTERS. 



Tiannae with 4 or more marginal tentacles. With 4 interradial horseshoe-shaped gonads 

 in the stomach-wall. Each horseshoe composed of partially fused swollen ridges. 



Lesson, 1843, describes three medusae under the name Turns, only one of which belongs 

 to the genus as we define it. This one is Turns neglecta of the north Atlantic coasts of Europe. 

 The name Tiara was also proposed by Lesson, 1843, and is used to describe a medusa which 

 was first observed by Forskal, 1775, under the name Medusa pileata. It is found off the 

 Atlantic coast of Europe and in the Mediterranean. 



I use Turris as equivalent to Turris Lesson + Tiara Lesson + Catablema Haeckel. 

 Haeckel, 1879, p. 62, establishes Catablema for a Greenland medusa which he calls Catablema 

 campanula. 



Maas, 1904, who embodies the results of the studies of Vanhbffen, Hartlaub, and himself, 

 defines Turns as having horseshoe-shaped interradial gonads, the sides of the horseshoe 

 being made up of partially fused, transverse ridges while the arch connecting the two sides is 

 composed of an irregular network of ridges. In Tiara the network is lacking, the entire 

 horseshoe being composed of more or less transverse ridges. The ridges do, however, anas- 

 tomose to some extent, so that an imperfect, partial network may be formed. Catablema he 

 distinguishes by the jagged edges of its radial-canals and circular vessel. However, medusa; 

 of Turns and Tiara often display lagged edges upon their canals, and this character is very 

 variable and subject to much individual irregularity in development. In the young medusa 

 of Catablema the ridges forming its interradial horseshoe-shaped gonads tend more or less 

 longitudinally, but in later development they come to he almost transversely as in Turns 

 or Tiara. In order to terminate the confusion that has been introduced by these intergrading 

 and too precise criteria for distinguishing the genera Turris, Tiara, and Catahlrma, I propose 

 to unite them all under one genus and call it Turns, the name first used by Lesson to dis- 

 tinguish any of these medusae. 



