282 ^н- Mortensen. 



by Düben & Koren. As a character of C. assimilis it is pointed out 

 by Düben & Koren that two of the tentacles are smaller than the 

 rest, and this has probably been the main reason for Lud wig's 

 uniting it with C. lactea, in which likewise tw^ of the tentacles are 

 smaller than the rest; but also in young C. frondosa the two ten- 

 tacles may sometimes be smaller, as I have been able to determine 

 in some cases. This feature is then no proof against C. assimilis 

 being a young С frondosa. Also the whole shape of the animal, 

 as represented by Düben & Koren, is much more like the 

 young С frondosa than С lactea. Finally it is scarcely justi- 

 fiable to suppose that Düben & Koren might mistake the young 

 C. lactea, which species they knew and described very well, while 

 it is easily understood that they could doubt, whether it was really 

 C. frondosa, since tbey did not know the true calcareous corpuscles 

 of that species. 



The calcareous corpuscles of Сие. frondosa have been figured by 

 Bell (Op. cit. PI. IV. Fig. 2). As these figures seem to me partly 

 less satisfactory. I have given a figure of such a corpuscle (PI. XVII. 

 Fig. 10). They are generally angular, rather thick, with round holes, 

 irregularly arranged, and between the holes are seen small promi- 

 nences, which appear as small clear spots in the calcareous matter when 

 viewed from above. In side view they are seen to be short tubercle- 

 like prominences, as is well shown by Bell. As these calcareous 

 corpuscles are generally very scarce or even totally wanting in the 

 grown specimens, while they are mostly numerous in the young 

 ones, they must probably be absorbed during growth; in fact, it is 

 not rare to find small, irregular pieces of calcareous corpuscles 

 in the skin of larger specimens, which may probably represent 

 absorption-stages. Sometimes, however, one may also find some 

 few developmental stages of calcareous corpuscles in larger speci- 

 mens. Generally the calcareous corpuscles have disappeared already 

 in specimens of ca. 20 mm length (in preserved, contracted stage). 

 The spicules of the tubefeet, as well as the plate of the sucking 

 disk, are generally not resorbed during growth. The shape of the 

 disk plate is very irregular; it is very weak, and the holes large 

 and irregular. In PI. XVII. Fig. 9 is represented the disk from a 

 young specimen, which is seen to consist of three separate plates. 



In PI. XVII. Fig. 13 is represented part of the calcareous ring of 

 a specimen 10 mm long. The radialia are somewhat widened in the 

 anterior part, which is hollowed in the middle, where the muscle 

 is attached; the anterior edge is slightly sinuated. The interradialia 

 are somewhat larger, with a narrow anterior part. The parts of the 

 calcareous ring are, upon the whole, very weak and little developed 



