120 Dr. Th. Mortensen on the 



d. deutschen Tiefsee-Exped. p. 157), and by Agassiz and 

 Clark (' Hawaiian and other Pacific Echini, Salenidse . . . 

 Diadematidre/ p. 100). I must confess that the fact that 

 Pomel names a species under each of his two genera, which 

 must evidently be regarded as the genotypes, seems to me to 

 outweigh the confusion he has made in the diagnoses. If we 

 had to refuse all those of the older genera which are in- 

 correctly diagnosed, what wonderful results would come about ! 

 When a genotype is designated it does not matter very much 

 whether the diagnosis is quite correct or not. The genotype 

 is the main thing, and as in this case it has been named by 

 Pomel, it seems to me that the name P lesiodiadema ought to 

 be maintained in spite of the erroneous diagnosis. But, as so 

 much can be said both pro and contra, the question ought to 

 be decided by the International Council of Nomenclature. 



The name Echinocyamus has also been very much dis- 

 cussed in late years. Lambert maintains that what is 

 described and figured under this name by Van Phelsum is 

 the high form now universally called Fibularia, not the flat 

 form common in European seas now universally known as 

 Echinocyamus. Accordingly he wants to have these two 

 names interchanged, and he has, in fact, done this in his later 

 works. In the ' Ingolf ' Echinoidea (ii. p. 38) I have 

 discussed the matter at some length, pointing out (1) that 

 Van Phelsum himself indicates that his specimens came from 

 the Adriatic (and America), where no high forms are found; 

 in the Adriatic Echinocyamus pusillus alone occurs, being 

 very common there, as is well known*: and (2) that the 

 enlarged figures given by Van Phelsum are quite impossible, 

 resembling neither the low nor the high forms among recent 

 species, while the unenlarged figures in any case resemble 

 much more the flat European species than the high East 

 Indian species. Accordingly I conclude that it is undoubt- 

 edly our common Echinocyamus pusillus which is the type of 

 Van Phelsum's genus Echinocyamus. 



To this Lambert objects, in his ' Description des Echinides 

 fossiles des terrains miocdniques de la Sardaigne,' that the 

 localities given by Van Phelsum are incorrect: — " On sait 

 d'ailleurs avec quelle facilite peuvent s'e^garer des Etiquettes 



* In his u Description des Echinides fossiles des Terrains mioce"niques 

 de la Sardaigne '' (Mem. Soc. Pal. Suisse, xxxiv. 1907, p. 38) Lambert 

 says : " Van Phelsum ne dit d'ailleurs pas comme le voudrait M. Mor- 

 tensen qu'il y a d'autres Echinocyamus dans l'Atlantique et l'Adriatique, 

 il affirm e que ces espeees, les types figures, en proviennent et c'est la sa 

 seule erreur." This must be a misunderstanding of my text. I do not 

 see that 1 have ascribed the error to Van Phelsum. 



