IS'J MKnrs.E OF THF. WORLD. 



Mature medusa. Bell 6 mm. high, 4 mm. wide. Pyriform. There are 3 tentacles in 

 each of the 4 radial, marginal clusters and only one tentacle in each interradius. The stomach 

 is mounted upon a short peduncle, and both together are hardly half as long as the depth of 

 the bell-cavity. There are 4 radially placed, simple, unbranched, oral tentacles, each of which 

 terminates in a knob-like cluster of nematocysts and is as long as the stomach itself. When 

 immature the medusa produces medusa-buds upon the interradial sides of the stomach, but 

 later, when there are 3 tentacles in each radial cluster, the budding ceases and ova or sperm 

 develop. Claparede discovered that the eggs are inclosed in nematocyst-beanng capsules, 

 reminding one ot'the condition observed in Bougainvillia superctliaris. Browne states that the 

 medusa may become sexually mature when the bell is only 1.5 mm. high. The stomach, 

 gonads, and tentacle-bulbs are amber-yellow. Found off the coasts of England, Ireland, 

 Scotland, Germany, and Norway. 



When the medusa is young there are only 8 marginal tentacles, 4 radial and 4 interradial. 

 Later there are 4 radial clusters, each consisting of 2 tentacles, and 4 smaller, isolated, inter- 

 radial tentacles. Medusa-buds are produced upon the interradial sides of the stomach, when 

 the medusa has only 8 tentacles. The 4 oral tentacles remain simple and unbranched through- 

 out life. 



Lizzin eliztihftlicr Haeckel resembles R. blondina in all respects excepting that there are 

 4 tentacles in each radial, and 2 in each interradial cluster. Haeckel found this at Jersey, 

 English Channel. May it not be R. blonJina with more than the usual number of tentacles ? 



Browne found a 3-rayed specimen of R. blonJina, with 3 radial-canals, j oral tentacles 

 } clusters of "perradial" tentacles each containing 2 tentacles and 3 single interradial tentacles 



Genus CHIARELLA Maas, 1897. 

 C\iiaTflla, MAAS, 1897, Mem. Mus. Comp. Zool. at Harvard College, vol. 23, p. 15. 



The type species and the only known form is Chiarella centripetalif Maas, from the 

 Gulf of California, Pacific coast of Mexico. 



GENERIC CHARACTERS. 



Margelina? in which the ring-canal gives rise to blindly ending, centripetal diverticula, 

 There are 8 cleft tentacle-clusters, so that the tentacles arise from 16 epaulet-shaped, marginal 

 swellings. 4 of these cleft tentacle-clusters are radial, and 4 interradial in position. The oral 

 tentacles are dichotomously branched. 



This genus is chiefly distinguished by the blindly-ending diverticula of the marginal 

 ring-canal. The deeply-cleft tentacle-epaulets are quite characteristic, but this tendency 

 is also seen in some species of Bougainvillia and can not he considered as being a distin- 

 guishing characteristic of Chiarella, although it appears in a more marked degree in Chiarella 

 than in Bougainvillia. 



Chiarella centripetalis Maas. 



Chiarflla centripelalh, MAAS, 1897, Mem. Mus. Comp.Zool. at Harvard College, vol. 23, p. 15, taf. 2, fign. 1-4; 190^, Craspe- 

 doten Medusen der Siboga Expedition, Monog. 10, p. 13. 



Bell high and dome-like, 15 to 20 mm. high, 10 to 15 mm. wide. Gelatinous substance 

 of slight consistency and fairly thick at apex, but thin at margin. Velum small. Bell-margin 

 exhibits 8 adradial, lappet-like emarginations which alternate with the radial and interradial 

 clusters of tentacles. The tentacles are very short, not more than one-tenth as long as the 

 bell-height and arising from 8 medianly cleft, marginal, epaulet-shaped swellings. The median 

 cleft in each tentacle-epaulet is so deep that the epaulet seems divided. 4 of these divided 

 epaulets are radial and 4 interradial in position. In the mature medusa there are somewhat 

 more than 40 tentacles in a single row on each double-epaulet, the medusa having altogether 

 about 320 tentacles. These tentacles arise side by side from the margin of the epaulets, and 

 the line of tentacles is continuous and not interrupted at the median cleft. There is an 

 ocellus upon the margin of the epaulet, on the velar side, at the base of each tentacle. 



There are 4 straight-edged, narrow radial-canals and a ring-canal. This ring-canal gives 

 off a short, pointed, blindly ending, centripetal diverticulum in each interradius above the 

 median cleft of each interradial tentacle-epaulet. 



