544 MEDUSAE OF THE WORLD. 



A single specimen was found by Haeckel at Algeciras in the Straits of Gibraltar. He 

 states that owing to the general transparency of the specimen and to its smallness he is able 

 to describe it only through reference to the larger species oiPeriphylla found by the Challenger 

 expedition. He states that the bell is 30 mm. high, 20 mm. wide, helmet-shaped. The pedal 

 zone nearly as wide as the lappet-zone. The 16 pedalia are of not quite equal size each to 

 each. The 16 lappets tongue-shaped, sharp-pointed, the 8 tentacular more projecting than 

 the 8 rhopalar lappets. 12 tentacles as long as the bell-height and one-third as wide as the 

 lappets at their bases. Basal, central, and buccal stomachs of nearly equal length. 



Color violet, bell more red, tentacles and throat-tube more blue, gonads dark-red. 



Periphylla hyacinthina Steenstrup. 



l'i-rifh\lla h\ac!nth!na, STEENSTRIT, 18(7, Acta Mus. Hafniensis. HAECKEL, 1880, Syst.der Mcdusen,p. 419, taf. 24, fign. n- 

 16. FEWKES, 1886, Report Commiss. Fish and Fisheries U. S. A., for 1884, p. 930. CI.AUS, 1886, Arbeit. Zool. Inst. der 

 Univ. Wien., Bd. 7, p. 99, fig. I, p. loo. AGASSIZ, A., 1888, Bull. Mus. Comp. Zool. at Harvard College, vol. 15, p. 1-51, 

 fig. 426. VANHOKFEN, 1891, Zool. Anzeiger, Jahrg. 14, p. 38; 1908, Deutsch. Sudpolar Expedition, 1901-03, Bd. lo, 

 Zool. 2, p. 36; 1892, Ergeb.der Plankton Expedition, Bd. 2, K. d., p. 6, taf. I, fign. l-io; taf. 2, fign. 3-8; taf. 3, fign. 1-7; 

 1902, Wissen. Ergeb. deutsch. Tiefsee Exped., Dampfer I'aldiria, Bd. 3, Lfg. I, p. 23; 1906, Nordisches Plankton, Nr. II, 

 p. 42, fig. I. BROWNE, 1903, Bergens Museums Aarbog, No. 4, p. 30. MAAS, 1904, Result. Camp. Sci. Prince de Monaco, 

 fasc.28, p. 47, plate 5, fig. 35; planche 6, figs. 45-46; ioc.6, Fauna Arctica, Bd.4, Lfg. 3, pp. 502,511 (review of literature). 

 BH.KLOW, H. B.. 1909, Mem. Mus. Comp. Zool. at Harvard College, vol. 37. p. 26, plates 1 and 9. 



Char\bdea hyacinthina, STEENSTRUP, 1842, Acta Mus. Hafniensis. 



The following description applies to the typical P. hyacinthina. 



This so-called species is distinguished by its high, narrow bell, the ratio of height to 

 width being usually about as 44 is to 23. The lappet-pouches are so densely pigmented with 

 dark purple-brown that the gonads can not be seen through them from the outside. 



Bell 80 mm. high and about 42 mm. wide, but it may be much flatter and wider (see fig. 

 343). The upper, or aboral, halt ot the exumbrella is dome-shaped or pyriform with a smooth 

 external surface. Just below this dome is a deep horizontal circular constriction which is 

 occupied by circular muscle-fibers. Below this constriction the exumbrella flares slightly 

 outward, and in this region we may distinguish an upper pedal-zone and a lower lappet- 

 zone. The pedal-zone is divided by 16 deep, longitudinal furrows into the same number of 

 projecting, wedge-like thickenings, the pedalia. The 4 interradial pedalia are smaller than 

 the others and lie in the radii of the 4 marginal sense-organs; while the 12 perradial and 

 adradial pedalia are situated in the radii of the tentacles. 



There are 16 well-developed marginal lobes, arranged in 8 pairs. 16 deep longitudinal 

 furrows lie in the mid-radial lines ot the lappets and separate the 16 pedalia, so that a furrow 

 extends about two-thirds the distance down the exumbrella surface of each marginal lappet. 

 The 4 interradial rhopalar clefts between the lobes are only about two-thirds as deep as the 

 12 tentacular clefts. Each sense-organ contains a proximal mass of dark-brown entodermal 

 pigment and a distal concretion, which is protected by an aboral fold forming a niche for its 

 protection. 



The 12 tentacles are equally developed and are each a little longer than the bell-height. 

 They are solid and are provided with well-developed, longitudinal muscle-fibers. In the 

 cavity of the subumbrella 4 long, funnel-shaped, interradial pits extend inwardly along the 

 sides of the central stomach nearly to the aboral apex, where their points do not quite touch. 

 There is a well-developed zone of circular muscle-fibers in the subumbrella just above the 

 bases of the tentacles and sense-organs. This zone is divided by 16 longitudinal selvages 

 into 16 distinct parts; each selvage extends down the middle ot a lappet, and thus the ad|om- 

 ing halves of each pair of adjacent lappets are connected by the circular muscles. Besides 

 the circular muscles, 8 well-developed, longitudinal muscle-strands lie in the inner, or proximal, 

 part of the subumbrella wall; 4 of these are perradial and 4 interradial. They are deltoid 

 in shape, their broad bases extending out into the distal part of the subumbrella, to the upper 

 part of the zone of circular muscle-fibers. There are 8 U-shaped gonads which are on both 

 sides of the 4 interradial septa, with their convexities directed outward; thus they appear 

 to be adradial in position and alternate with the 8 longitudinal muscles of the inner part of 

 the subumbrella. 



The stomach extends from the inner apex of the subumbrella to about the level of bell- 

 margin. Its cavity may be divided into 3 regions, which we may designate, respectively 



