no. 1761. .1 NEM SPECIES OF ONCHIDIOPSIS i:\l.cil. }7<) 



As to the troublesome Marseniopsis, it seems closer to the Velu- 

 tininse than to the Lamellariinse. The extraordinary aberranl radula 

 of the latter is a tangible and strong point of demarcation in which 

 no error of observation or interpretation is likely. It is an unbridled 

 gap, and Marseniopsis is here wholly with the Velutininse. As to 

 the two characters which ally it with the Lamellariinse, the expiratory 

 cleft, has already been commented on, while for an appreciation of 

 the slight and almost technical character «,f the line separating 

 androgyny from unisexuality in the gasteropods Pelseneer's paper 

 should be consulted (Pelseneer, 1N<)4). 



Since the last of Bergh's writings on the group the Australian 

 genus Oaledoniella Souverbie 1869, hitherto known only from the 

 shell," lias been partially elucidated by Basedow [1905]. The shell 

 is wholly internal, thin, incompletely calcified, but otherwise qo< 

 very degenerate, and consists of 3 + whorls. It is strikingly naticoid 

 in appearance. The radula has the formula 2 — 1 — 1 — 1 — 2 and in 

 general resembles those found in the Yelutinime — i. e., is naticoid. 

 We do not know whether the animal is monoecious or dioecious. Base- 

 dow's figures do not show any expiratory cleft or fold, hut in his 

 generic diagnosis he says:— "renal aperture on the right, the mantle- 

 border slightly grooved outward from this spot," which may indicate 

 that the fold is present in rudimentary form. The anatomical data 

 are insufficient for placing the genus with entire confidence, but so far 

 as known ally it with Marsenina and Ouchidiopsis in the Velutininse, 

 where it would lie near the base of the series. Two things, however, 

 throw doubt on the correctness of this disposition. First . if Marsi nina 

 and Ouchidiopsis are really (as believed) derived from the naticoids 

 through velutinoids, then it is difficult to sec how Oaledoniella can be 

 introduced into the series, with a shell which, though more degenerate 

 than any Velutina, appears to relate back direct to Natica. Second, 

 Oaledoniella is an Australian form, thus geographically suggesting 

 alliance with the Lamellariinse, which though world-wide are espe- 

 cially tropical and austral, rather than with the Velutininse, which are 

 essentially boreal. It may be suspected that if all the facts were 

 known Oaledoniella would be seen to be a basal term of the Lamella- 

 rioid series, its apparently greater resemblance to the Velutininse being 

 purely negative and due to its not yet having acquired the peculiari- 

 ties of dentition and generative system which mark the typical Lamel- 

 larioids. This implies that the family Lamellariidse is diphyletic, 

 which is probably the case. But such suspicions can not be allowed 

 to override the evidence as it stands and Oaledoniella must for the 

 present rest among the Velutininse. 



The group considered as a whole is, at all events, a most interesting 

 offshoot from the naticoid stem, representing evolution in the same 



" The animal described by E. A. Smith 1 1886] as Lamellaria wilsoni appears to have 

 been in fact, a Caledonu I In. but the description is not sufficient to be of use 



