148 



ACTINIARIA 



The identification of the Arctic and North-American Cribrinidae has till now been rather difficult. 

 True enough, it is easy to distinguish Cribrina stetta from other forms, though alcoholic specimens of this 

 species have possibly been confounded in the literature with the below described C. spetsbergensis, but some 

 of the other forms, especially specimens without reproductive organs, agree so well with each other that in 

 certain cases it is almost impossible to distinguish them, if we do not make use of the dissimilarity of the 

 nematocysts as a means of identification. Through a systematic examination of the size of the nematocysts 

 in a great number of specimens I have, however, been able to distinguish several Cribrinids which have 

 certainly been more or less confounded with each other by several authors, myself not excepted. After having 

 laid a sure foundation through a study of the size of the nematocysts I have, little by little, found other char- 

 acters usable as distinctive marks to the different genera and species. The importance of a closer study of 

 the nematocysts in order to classify the Actinians which I have several times emphasized stands out 

 here in the most striking manner. 



Whether any of the species, mentioned below by myself, have been described before can hardly be 

 decided as the North-American Cribrinids are more or less imperfectly known, especially as regards their 

 nematocysts. No satisfactory answer can be given to this question, until the nematocysts of the North- 

 American forms have been subject to closer examination. 



Genus Cribrina Ehr. s. Bunodactis Verr. 



Diagnosis: Cribrinidae with a well developed pedal disc. Column with suckers (verrucae), arranged 

 in more or less distinct lines, without true acrorhagi, sometimes with pseudo-acrorhagi. Sphincter strong. 

 Tentacles from short to of ordinary length, simple, like the mesenteries hexamerously arranged, in certain 

 species after another number or irregularly arranged. Longitudinal muscles of the tentacles and radial muscles 

 of the oral disc ectodermal, sometimes with a tendency to be a little mesogloeal. Most often 2 distinct siphono- 

 glyphes. Numerous perfect mesenteries. Reproductive organs on the first cycle (sometimes not developed 

 on the directive mesenteries) and on the other stronger mesenteries.. 



In my paper 1899 I have put forms furnished with real acrorhagi together with Cribrina. That is 

 however not right, but such species as Bunodes hermafroditica might be referred to Anthopleura. Whether 

 such species, having pseudo-acrorhagi, belong to Cribrina or to Anthopleura, is difficult to decide. Mc.Murrich 

 refers them to Cribrina, and for the present I do the same, though it would perhaps be more correct to arrange 

 them with Anthopleura, as the pseudo-acrorhagi may be regarded as beginning acrorhagi. 



Cribrina Stella (Verr.) Me. Murr. 

 PActinia coriacea Stimpson 1853 p. 7. 

 Bunodes Stella n. sp. Verrill 1864 p. 16. Pi. i figs, i 8, 1868 p. 258. Andres 1883 p. 447. Parker 1900 



P- 752- 



Bunodactis stetta (Verr.) Verrill 1899 p. 43. 

 Cribrina stetta (Verr.) Me. Murrich 1910 p. 76 PI. 3 figs. 67. 

 Bunodactis spectabilis Verrill 1879 a p. 15, 1879 b p. 152. 



