178 



PROCEEDINGS OF THE \ \ll<>\ 1 /. \l I 8EI M. 



vol. 38. 



by Woodward [1880], Tryon [1886], Fischer [1887], Cooke [1895], 

 Simroth [1896 L907], and most other systematists, some calling the 

 resulting family Lamellariidse, some Velutinidse. 



Bergh himself recognized that the genera Onchidiopsis and Mar- 

 senina, al least, might be united with the Velutinidse were it not that on 

 the other hand they connect through the puzzling genus Marseniopsis 

 with the irreconcilable genera ( 'lidynotus, Lunn Ihn -id, and M(irx< nulla. 



Bei'irh summarized his views in the following: 



CONSPECTUS GENERUM. 



Plica expira- 



to] ia nulla . 



| . Irmatura 

 lingnalis] 



1-1-1 



dioecious. 



Plica expira-j 

 toria [ 



3 I 3 



Pars inf. vasdefer. nun 

 libera < In lynotus Sw. 



(Miirs, a in I. cadi | 

 Lamellaria] 

 Mm. s< nil I In Bergh 

 Test. int. calcarea Marseniopsis Bergh . 



Test, semi-int. calcarea.. Marsenina Gray 



... . T monoecious 



rest. int. comma Onchidiopsis Bergh 



It is apparent that , but for the contradictory characters of Marseni- 

 opsis, the genera would fall apart in two well-marked groups, which 

 may he called the Lamellaria group and the Onchidiopsis group, the 

 latter then clearly uniting with the Velutinidse, which agree in every 

 essential respect, especially dentition and hermaphroditism, except 

 that the shell is still external and, of course, the expiratory fold is 

 therefore not developed.'' In short, the group considered as a whole 

 would appear as either monophyletic but sharply divergent, or as 

 di-phyletic and partially convergent. 



The introduction of Marseiriojws into the scheme makes any 

 orderly phylogenetic interpretation impossible — that is to say, it 

 makes any true arrangement impossible. We must, therefore, for 

 any conclusion, await new fads, particularly as to Marseniopsis, 

 which it would be desirable to investigate further. The bearing of 

 the new species which is the subject of this paper on the situation is, 

 by its shell structure, to draw Onchidiopsis closer to Marsenina, par- 

 tialis bridging the gap and indicating in a most interesting way the 

 precise manner in which the still whorled shell of Marsenina has 

 degenerated, in this series, to the mere scale of the other species of 

 Onchidiopsis. 



"The hermaphroditism of Velutina rests on the hare casual mention of Bergh. So 

 interesting a fact should be verified. The preBen ed material al my command has qoI 

 permitted this. There is reason to BUBpect, as Simroth eBpeciallj has suggested, that 

 hermaphroditism among the prosobranchs may be much mure Erequenl than commonly 

 supposed. 



i> Ii is difficult to understand the high morphological significance Bergh appears to 

 attach i" this obviously plastic feature. The fold is in fact scarcely bo much an 

 anatomical character 1 as an habitual manner n\ carrying the mantle border. The 

 Bpecimen examined by me suggests the idea thai in life ii might have been "hi it era ted 

 and re torn led at w ill. 1 1 can at least have no systematic importance in a phylogenetic 

 aeries commencing with a shell-covered form. 



