c ACTINIARIA 

 146 



■phellia and that of Epiactis only a difference in degree, in as much as the cuticle is stronger in the former 

 species, weaker in the latter. As Epiactis and Pseudophellia agree in other characters too, Pseudophellia, 

 which is synonymous with the older Epiactis, may be dropped, and the type of Pseudophellia be called 

 Epiactis arctica. Cribrina, Urticina and Ixalactis are, to my mind, rather well defined genera. Whether 

 Epigonactis is synonymous with Urticina or not is, however, very dubious and cannot be decided until the 

 genus has been subject to a careful anatomical examination — I have before (1901 p. 483) placed this genus 

 together with Epiactis, and Stephenson (1918 a p. 27) was of my opinion. Finally I do not think that 

 Anthopleura and Bunodosoma, which Mc. Murrich has placed together to a single genus, are identical. As 

 far as I can see from Mc. Murrich's description of the verrucae of Anthopleura xantogramma and A. (Au- 

 lactinia) stelloides they are in structure like those of Cribrina and Urticina and are real suckers to which foreign 

 bodies are attached, while the ampullaceous off-shoots in Bunodosoma are constructed in a different way, 

 and, according to my examination, more in accordance with the prominence of the column of Phymactis and 

 Cystiactis. Thus the ampullaceous off-shoots of the column of Bunodosoma are not suckers, but rather to be 

 considered as weak batteries of nematocysts to which no foreign bodies are attached. Mc. Murrich (1889 

 p. 24) himself has emphasized this difference, but later on (1901) not made use of it for systematic purposes, 

 in which he was mistaken, as far as I can understand. 



The characters which distinguish the genera of this family from each other are first of all based on 

 the presence of acrorhagi, further, on the occurrence or non-occurrence of real suckers and ampullaceous 

 batteries of nematocysts on the column, on the exterior of the tentacles and the arrangement of their long- 

 itudinal muscles and of the radial muscles of the oral disc, on the distribution of the reproductive organs in 

 the mesenteries and on the arrangement of the latter. The importance of these characters to the classification 

 however wants further discussion. 



The absence or presence of acrorhagi is no doubt a good character, as no variation occurs within the 

 genera in this respect, but these characters are either present or absent in the respective genera. On the other 

 hand, the systematic importance of other differentiations of the column is partly totally different. It is true 

 that the ampullaceous papillae are characteristic of Bunodosoma and always present here (as in Anthopleura 

 this genus is characterised through the presence of acrorhagi), but the appearance of suckers is evidently 

 subject to variation, in as much as the same genus and the same species now have suckers, now are devoid of 

 such. This is the case with Urticina. It is also possible that the below described, new genus Cribrinopsis, 

 which is typically furnished with suckers, sometimes is devoid of them. The absence of discernible suckers 

 in strongly contracted and badly preserved specimens should not, however, absolutely be interpreted as if 

 suckers were in reality lacking, the suckers of such specimens not being easily discernible to the naked eye, 

 not even under high magnifying powers. Thus it is only with great caution that we may use the presence 

 or absence of sucking warts as a systematic character, as mentioned before by Mc. Murrich. In the other 

 genera, Cribrina and Anthopleura, the occurrence of verrucae seems to be constant, wlrile the genus Epiactis 

 is always devoid of verrucae. 



The longitudinal muscles of the tentacles and the radial muscles of the oral disc are now mesogloeal, 

 now ectodermal and commonly constant in the respective genera, though also here a certain variation some- 



