22 EDWARD T. BROWN K. 



centripetal canals. The characters selected for the genus would make very good 

 specific characters. Chiarella centripetalis was found by Agassiz in the Gulf of 

 California. 



KOELLIKERIA MAASI. 



(Plate IV., fig. 1-5.) 



Description of the Species. Umbrella very thick, a little higher than broad, with 

 a rounded summit. Stomach fairly large, . cross-shaped, and internally covered with 

 papillae. Four oral tentacles, each of which is many times dichotomously branched. 

 Four broad radial canals. Gonads separated perradially into four masses, which cover 

 very nearly the whole wall of the stomach. Eight groups (four perradial and four 

 interradial) of marginal tentacles, each group containing seven tentacles, of which the 

 central tentacle is the largest. Compound basal bulbs of the tentacles very incon- 

 spicuous. Ocelli absent. 



Size. Umbrella up to 9 mm. in width and 10 mm. in height. 



Description of an Early Stage (Plate IV., fig. 1). Umbrella moderately thin, with- 

 out a mass of jelly above the stomach and slightly higher than broad. Stomach small 

 and cross-shaped, about one-third the length of the umbrellar cavity. Four oral 

 tentacles, each of which is 2-3 times dichotomously branched. Four fairly broad 

 radial canals. Eight groups of marginal tentacles, each group containing three 

 tentacles, of which the central one is the largest. Umbrella about 1 5 mm. in width. 



It is a pleasure to me to associate this new species with the name of Professor 

 Otto Maas. 



There are twenty-four specimens of this Medusa in the ' Discovery ' collection. 

 The specimens, especially the larger, were difficult to examine, owing to the contraction 

 of the umbrellar margin and to its curling far up into the interior of the umbrellar 

 cavity. For the drawing (fig. 2) of the adult several specimens were used. Its 

 outline may not be quite correct when compared with a living specimen. It shows, 

 however, the characters of the species. 



The specimens were taken from May to December, 1903. As the early, 

 intermediate, and adult stages occurred during May, and different stages of develop- 

 ment during the other months, it is probable that the Hydroid has no definite 

 breeding period. 



The stomach in transverse section has the shape of a cross, and is attached at 

 its base to the radial canals. Its interior is covered with minute endodcrmal 

 papillae (0 1 to 3 mm. in length), which are formed by outgrowths of the wall 

 of the stomach. A series of sections, from a specimen which happened to be in a 

 fair state of preservation, shows that the cells of the papillge are similar to those 

 which form the endodermal wall of the stomach (fig. 5). Along the centre of the 

 papilla runs a slender strand of mesoglsea, which is in continuation with the mesoglsea 

 between the ectoderm and endoderm in the wall of the stomach. 



