174 THE VOYAGE OF H.M.S. CHALLENGEE. 



Amphidetus ; we are either led to unite these genera into one genus, as has been proposed 

 by Gray, and recognise Breynia and Lovenia merely as sub-generic types, or we are 

 almost forced to establish for every species a different generic section, so gradually do all 

 the characters upon which these genera are usually distinguished pass into one another. 



Breynia, Echinocardium., and some species of Lovenia correspond remarkal^ly well in 

 the structure of the posterior extremity of the test ; while Breynia and Echinocardium 

 agree well in the structure of the actinal surface, yet in Echinocardium we can see the 

 beginning of the sinking of the scrobicular area so specially developed in one of the 

 species of Lovenia proper, while in Breynia and Lovenia, both have a peripetalous 

 fasciole or a partial lateral fasciole, and Breyyiia, Lovenia, and Echinocardium all agree 

 in the structure of the petals and in having an anterior intrapetalous fasciole. Breynia 

 and some species of Echinocardium agree in having no unduly developed large primary 

 tubercles below the petals, and the few larger primaries are placed within that area ; 

 the large primaries of Lovenia on the abactinal surface showing their relationship to 

 Spatangus, Maretia, and the like ; while in such species of Echinocardiicm as Echino- 

 cardium flavescens, it would be difficult to separate it from Breynia except for very 

 unsatisfactory reasons (the shape of the test and the presence of a peripetalous fasciole). 

 The greater number of primary tubercles in the anterior part of the test of these species 

 is, on the contrary, a feature which allies them to Lovenia as well as the slight beak 

 formed over the sunken anal system, which is still more prominently developed in 

 Echinocardium pennatifidum. As will be seen from the analysis of Breynia and Lovenia 

 it is evident that these genera and Echinocardium are very closely related, and might 

 very properly be considered as sub-genera only of Echinocardium. 



Echinocardium australe. 



Eehinocardium australe, Gray, 1851, Ann. Mag. Nat. Hist., jx 131. 



A good series of specimens of this species was collected ; they show that the characters 

 which have been used to distingiiish Echinocardium australe from its Atlantic congener, 

 Echinocardium cordatum, are reduced to differences in the shape of the anal system, the 

 position of the apical system and the difference in outline of the profile of the test, with 

 the slight difference in the distances of the pores of the petals. These differences are 

 thus far quite constant in all the specimens I have examined, but seem very slight ground 

 for maintaining the specific distinctness of the Pacific and the Atlantic representatives of 

 the genus, and I should expect that additional material will prove this species to be 

 identical with the European species, and to have, like a few other species of Echinids, a 

 most extensive geographical as well as bathymetrical range. 



Kobe, Japan ; 7 to 8 fathoms. 



Station 234. June 3, 1875. Lat. 32° 31' N., long. 135° 39' E.; 2675 fathoms ; 

 bottom temperature, 1*4° C. ; grey ooze. 



