34 EDWARD T. BROWNE. 



This is the type genus of the family and contains four species, namely, M. annse, 

 Haeckel, 1864, M. minervee, Haeckel, 1879, M. mbengha [sic], Agassiz and Mayer, 1899, 

 and M. discoidea, Torrey, 1909. 



COSMETIRELLA SIMPLEX. 



(Plate I., fig. 6-8.) 



* 



For the generic characters, see p. 32. 



Description of the Species. Umbrella hemispherical, a little broader than high, 

 and fairly thick. Velum narrow. Stomach quadrilateral and short. Mouth with four 

 small lips having a slightly folded margin. Four radial canals. Gonads linear or 

 cylindrical, extending over the central third of the radial canals. Thirty-two or more 

 tentacles, having rather large conical basal bulbs, and usually a tentacular bulb between 

 every two tentacles. Eight adradial sensory pits on the velum, containing several 

 otocysts. 



Size. Umbrella up to 7 mm. in width and 6 mm. in height. 



Three specimens were taken by the ' Discovery ' amongst pack ice in lat. 66 52' S., 

 long. 178 15' E. on 3rd January, 1902. One of them is at an intermediate stage of 

 development, and has nineteen fully formed tentacles and about as many tentacular 

 bulbs or tentacles in the process of development. 



In the ' Southern Cross ' collection there are two specimens which were taken at 

 Cape Adare on 27th November, 1899. In my preliminary report upon the collection I 

 mentioned these specimens under the name of Phialidium, and also stated that the 

 marginal sense organs were not visible. They were visible, but I did not recognise 

 them owing to the invisibility of the otocysts, which had lost their refrangibility in 

 formalin.* After finding the sense organs in the ' Discovery ' specimens, and thus 

 knowing exactly what to look for, I again examined the ' Southern Cross ' specimens 

 and found the sensory pits. 



The ' Southern Cross ' specimens are similar to those in the ' Discovery ' collection, 

 except that the tentacles are very much longer and have larger basal bulbs, and the 

 velum is a little broader. 



There is a specimen in the ' Discovery ' collection taken under the ice in McMurdo 

 Sound on 16th March, 1903. It has evidently undergone a considerable amount of 

 contraction and shrinkage, as the umbrella has become a flat disc about 7 mm. in 

 diameter. There are forty-nine tentacles and thirteen sensory pits. The sensory pits 

 are irregular in position, and their number in-each quadrant is 4, 4, 3, 2 respectively. 

 The gonads are large, cylindrical in shape, and look about ripe. It may be the fully 

 grown adult of this species with an abnormal number of sense organs. 



Another specimen in the 'Discovery' collection was taken during May, 1903. 

 The umbrella is about 8 mm. in height and 5 mm. in width. The specimen is in 



* This is a fact about the use of formalin which is new to me, and should. I think, be noted. ED. 



