\\Tim\ii.Di s i; CI..\I>H\I:M \. 101 



body of" the hydranth Is pale reddish and the perisarc bright yellowish-brown. The medusae 

 are produced in spring and summer. 



Dujardin's, 1843, observations upon Cladonema niJintiun are the earlit-st in which the 

 complete life-history ot' the alternation of generations between hydroid and medusa was 

 actually observed. 



Cladonema perkinsii Mayer. 

 Plate 9, fig. i . 



C.lailonema, sp., PERKINS, 1902, Johns Hopkins Uimersitv Circulars, vol. n. No. 1^5. p. 2^, ne,^. in ti-it. 



Cladonema per kin sii, MAVFR, 1904, Memoir- N.it. Sci. Brooklyn Inst. Arts ami SM .. vol. i , XL. i . p. i X, plate 4, fig. 35. H*KT- 

 LAi'B, 1907, Nonlisches Plankton, Nr. 12, p. i ;^, tit:, it>. 



Bell half-egg-shaped; less than 2 mm. in diameter, with thin, uniform walls. 8 lar<;e, 

 stout, marginal tentacles. The inner and lateral parts of each of these tentacles bear 3 to 10 

 small, flexible cirri, which are besprinkled with wait-like clusters of nematocysts and termi- 

 nate in a knob. 1 here is a large, cup-like, ectodermal ocellus upon the outer side of each 

 main tentacle shaft near the bell-margin. The velum is large and shows circular striations. 

 Manubrium large and spindle-shaped, with about n rounded, protruding pouches at its widest 

 part. The mouth is surrounded by a circlet of 5 simple, short oral tentacles each terminating 

 in a knob-like mass of nematocysts. 8 simple radial-canals, 45 apart, arise hum the stomach, 

 and extend straight unvard the simple circular vessel. The manuhrium is thus 8-sided at 

 its proximal end, 6-sided in the middle, and 5-sided at the mouth. The genital products 

 develop in the ectoderm ot a large part ot the manubriurn and also in the hernia-like pouches. 

 The ocelli are black and all other parts colorless. This species was discovered by Professor 

 Perkins in Nassau Harbor, Bahamas, in July, 1902, upon the surface in shallow water at 

 night. 



Cladonema mayeri Perkins. 

 Plate 9, figs. 2 an, I -, . 



Cladonema, .</>., FKWKES, iSS^, Bull. Mus. Comp. Zool. at Harvard College, vol. 11, p. 87. 



Cladonema ma\eri, PKRKINS, 1906, Year Book of tile Carnegie Institution of Washington, No. 4, IIJCK. p. llS. KjoS, Papers 

 from Tort u gas I. ah. Carnegie In ^t. Washington, \ol. i , p. i ;(>, plate- i an, I 2. plate 4, figs. 2 t , 22. H\ ,!roul an, I medusa. 



Bell thin-walled, higher than a hemisphere, and with small, solid, apical projection; 

 top rounded and dome-like, and total height about 2.5 mm. There are 9 marginal tentacles, 

 one at the toot of each radial-canal. Each ot these tentacles has a large, spindle-shaped basal 

 bulb, the entoderm of which contains a mass of white concretions. On the outer side of 

 each basal bulb near the circular canal there is a deep reddish-brown, ectodermal pigment 

 spot. The distal, inner side of each basal bulb gives rise to about 6 small tapering peduncles 

 which terminate in small knob-like adhesive disks. These enable the medusa to cling to the 

 sides or bottom of the aquarium. The main shaft of each tentacle extends outward from the 

 spindle-shaped end of the basal bulb. It is umtorm, thread-like, and slender, and gives rise 

 to 4 to 8 thread-like side branches each ot which, together with the central shaft, terminates 

 in a knob-like cluster ot nematocvsts. There are 4 to 6 nematocyst-warts upon each side 

 branch and a greater number upon the main shaft. Both the main shaft and the side brandies 

 are highly contractile and can be expanded so as to become longer than the bell-height, or 

 contracted into a close bunch. The velum is very wide and its orifice small. 6 radial-canals 

 arise from the stomach, but every alternate canal bifurcates near its point ot origin, and 

 thus () equally spaced canals reach the circular vessel. The manubrium normal!) extends 

 to the level of the velar opening, but may contract somewhat at times, as is shown in our 

 figure. The mouth is surrounded by <> simple oral tentacles, each of which terminates in 

 a large nematocyst-knob. Near the middle of the stomach there is a circlet of 6 radially 

 arranged, short, blunt, hernia-like projections. The genital products are developed in the 

 ectoderm of the walls of the manubrium. 



The color is quite variable. The entoderm ot the basal bulbs ot tin- marginal tentacles 

 is milky-yellow streaked with dark-brown pigment-granules, while the entoderm of the 

 manubrium is milky-yellow or dull-milky ocher, streaked longitudinally in each of the ft 

 radii by dark-brown, almost black, pigment-granules. The disposition and arrangement ot 

 this pigment is highly variable. Perkins, iijoX, nives the most complete account ot this 

 medusa and its hydroid. 



