HYDROCOKALLINE GENUS El!JRIi\A. 893 



According to Ridley the coenenchymal canals of L. moseleyi and 

 L. antarctica are 0"035 to 0"07 mm. in diameter, the meshes 

 between the canals are about the same diameter in L. moseleyi^ 

 but in L. antarctica they var}^ from the same diameter up to 

 0'14 mm. Ridley does not state how his measurements were 

 obtained, consequently the results I have obtained cannot be 

 compared with his results wath any degree of precision. 



I have measured the diameter of a number of canals that have 

 been cut transversely in my sections at a level corresponding 

 with the base of the dactylozooids, and I find that the average 

 diameter of these canals is in Errina (Lahiopora) novce zelandice 

 0"03 mm. and in Errina {L.) capensis 0'05 mm. As the specimens 

 must have undergone very considerable contraction during de- 

 calcification and imbedding, I have regarded the measurements of 

 the meshes as worthless. All that can be said is that in both 

 species the meshwork of canals is close and elaborate. 



In the ' Challenger ' monograph Moseley gives as a character 

 of the genus Errina that the number of tentacles on the gastero- 

 zooids is four. In the Siboga species of Errina the number of 

 tentacles varied from four to five. 



In Errina (Labiojjora) novce zelandice I have found some difli- 

 culty in counting the number of tentacles, but judging from a 

 single series of sections, there are not more than four. In the 

 specimen of Errina {Lcihiopora) capensis, however, a very large 

 number of gasterozooids can be clearly seen without decalcification, 

 and in these the number varies from four to six. From this fact 

 it is obvious that the number of tentacles on the gasterozooids 

 cannot be relied upon as a generic or even as a specific character. 



List of the /Species of the Genus Errina. 



A. Ccenosteum hard and compact, perforated by well-defined 

 ccenosteal pores. Grooved spines turned towards the apex 

 of the branch. 



1, With shoi-t grooved spines and only one kind of dactylopore. 



The Errina group. 



Errina lahiata Moseley. 



Errina ramosa Hickson & England. 



Errina horricla Hickson & England, 



Errina carinata Pourtales ? 



Errina pourtalesii Dall ? 

 *ErrhLa glabra {= Lepiclopora glabra Pourtales). 

 *Errinco cochleata { = Lepiclopora cochleata Pourtales). 

 * Errina clabneyi { = Lepidopora dabneyi Povirtales). 



2. With long grooved spines and two kinds of dactylopores, 



Errina echinata ( = Spinipora echinata Moseley). 



* See Note, p. 894, 



