Ill MKDrS.E OF THE WORLD. 



Stomotoca divisa Maas. 



Siomoioca Jk'isa, MAAS, 1897, Mem. Museum Comp. Zool. at Harvard College, vol. 23, p. u, taf. i, fign. 1-9. 



Bell 20 to 30 mm. wide, 15 to 20 mm. high. Upper part of bell thick, solid, and dome- 

 like, and separated by an annular furrow from the thin-walled, marginal part of bell. This 



furrow may be due to contraction ( ?) A 

 very small, pointed apical projection arises 

 sharply from the aboral surface of the 

 evenly rounded dome of the bell. There 

 are 2 tapering tentacles about as long as the 

 bell-height. These appear to have some- 

 what more swollen basal bulbs than are seen 

 in S. pterophylla. There are no ocelli. There 

 are a large number of rudimentary tentacle- 

 bulbs as in S. pterophylla. The bell is trans- 

 parent with yellow entoderm, and with 

 orange to cinnabar-red gonads. 



IMI.. 61. Stomotoca Jivisa, after Maas, in Mem. Museum Comp. It IS found in the Bay oi Panama, 



Zool. at Harvard College, showing different statesof P ac jfi c coast o f Central America, ill March, 

 contraction of the bell. -.......,- ... . 



It is distinguished from the closely allied 



.S\ pterophylla of the West Indies by its brilliant coloration, S. pterophylla being constantly 

 dul I -brown. 



Perigonimus jonesii Osborn and Hargitt. 

 Plate n, figs. 3 and 4. 



Perigonimus jonesii, OSBORN and HARGITT, 1894, Amer. Naturalist, vol. 28, p. 27, figs. 1-12. HARGITT, 1895, Mittheil. Zool. 

 Station Neapel, Bd. u, p. 479; 1904, Bull. U. S. Bureau of Fisheries, vol. 24, p. 33, I fig.; 1901, American Naturalist, 

 vol. 35, p. 308, fig. 4; p. 579, fig. 37. NUTTING, 1901, Bull. U. S. Fish Commission, vol. 19, pp. 331, 372, fig. 80. 



} oung medusa. None of the specimens yet seen were mature. Bell of largest 2 mm. 

 in height and side walls extremely thin and flexible. There is a very small, dome-shaped 

 apical projection. There are 2 well-developed, diametrically opposed tentacles, which are 

 situated at the bases of 2 of the radial-canals. These tentacles are of unequal length and 

 are at times carried curled in a close helix and at other times are extended to their full length, 

 in which case one of them becomes about as long as the bell-height, while the other attains to 

 about twice this length. The basal bulbs of these tentacles are long, conical, and hollow 

 and have no ocelli, and the shafts of the tentacles are thickly covered with nematocyst-cells. 

 In addition to these well-developed tentacles, there are 2 small tentacle-bulbs, situated at 

 the bases of the 2 radial-canals 90 away from the long tentacles. There are no ocelli. The 

 velum is wide and flexible. There are 4 straight, slender radial-canals and a narrow, circular 



' O 



tube. The manubnum is short and simple, with a wide base and 4 simple, cruciform lips. 



The ectoderm of the manubrium and tentacle-bulbs is of a dull ocher-yellow. 



This medusa is very rare; only 3 specimens have been seen by me during 3 summers' study. 

 All of my specimens were found in Newport Harbor, Rhode Island, during July and August. 



Hydroid. The hydroid has been described by Osborn and Hargitt, 1894, from Cold 

 Spring Harbor, Long Island, New York, where it is found very commonly upon the abdomen 

 and upon the walking legs of the spider-crab (Libinia emarginata). It is a Pengoniiniis. 

 The stems arise from a creeping hydrorhiza and branch luxuriantly. The oldest polypite is 

 found at the distal end of the stem. The stems are covered with a thick gelatinous pensarc 

 which extends up the stems to the level of the tentacles, to which it is fastened. There are 

 normally 16 tentacles in a single circlet around the base of the hypostome. These assume an 

 alternately reflected position. The medusa-buds arise in clusters from near the center of the 

 stems. They are covered with the thick perisarc and each one is attached to the stem by 

 means of a well-developed peduncle. When set free the medusa has 2 diametrically opposed 

 tentacles which are usually carried turned inward into the bell-cavity. The hydroid is flesh- 

 colored. 



The medusa can at once be distinguished from S. apictita by the extreme tenuity and 

 flexibility of the bell-walls. The bell is also higher and narrower than in S. apicata The 



