ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
769 
allied to the Tectibranchiata, and have no closer relations to the Nephro- 
pneusta than the latter have to the Tectibranchiata. The fundamental 
error which led to the formation of the group Pulmonata is the compari- 
son of the higher forms of the two orders which are united in it. Now 
that we know the mode of development of the Nephropneusta in its 
general lines we see that when we compare the lowest Branch iopneusta 
with the Nephropneusta the agreement is very slight and quite general. 
An important point, hitherto noticed only by P. Fischer, is that we 
have learnt to distinguish the primarily naked Nephropneusta from those 
that are secondarily naked. The former or Meganota are chiefly repre- 
sented by the Peroniidae and the Vaginulidae. In Peronia, as in all 
the marine naked Mollusca, the shell is only a larval organ. This larval 
shell is continued on to the adult stage in no Nudibranch, though it is in 
some Saccoglossata, and in nearly all Tectibranchiata ; in this way it 
happens that naked and shelled forms may be found in the same 
family. 
There are many difficulties in the way of a direct derivation of the 
Nephropneusta from the Tectibranchiata, but there are many signs of 
their having had a common origin in some primitive form, unknown to 
us. It is of importance to take note of the developmental series among 
the Nephropneusta as well as genetic relations to other Ichnopoda. 
If we follow up this series we see that it is impossible to continue to 
allow the existence of an order Pulmonata. The author directs attention 
to the value of a research into the homologies of the spiculum amoris, and 
the demonstration of the absence of a receptaculum seminis in certain 
Nephropneusta ; a study of the homologies of the penis and its retractors 
in the Nephropneusta will, with the other lines of investigation, show 
that a family of Helicidae must be separated from a number of snail-like 
Mollusca, which have hitherto been associated only because of the 
characters of their shells ; this family can be broken up into genera in 
a way which the conchologist will allow to be natural. 
Morphology of Prosobranchiata.* — Dr. B. Haller describes in 
detail the anatomy of Naticidae and Calyptraeidaa. As regards fore-gut 
and a portion of the kidney, the Naticidae recall the more primitive 
conditions found among the Taenioglossae ; as regards gills and the state 
of the visceral sac in Sigaretus they approach the Calyptraeidae — an 
aberrant group w T ith adaptations for life among the rocks. As regards 
the genital apparatus, a portion of the kidney, and especially the nervous 
system, Natica, Sigaretus, and the Marseniidae are related to the 
Bhachiglossae. There seems no doubt as to the derivation of Calyp- 
traeidae from Sigaretus. The genera Crucibulum and Calyptrsea must be 
held as representing a younger form than Crepidula, Erg sea , and 
Janacus, but they are somewhat divergent from the main line. Partly 
on the strength of his own studies, partly on account of Bouvier’s, Haller 
believes that the Taenioglossae, derived from Architaenioglossae ( Cyprsea , 
Cyclophorus, Paludina ), must be divided into two great groups — Brevi- 
commissurata (more or less holostomatous) and Longicommissurata 
(siphonostomatous). The new terms refer to the cerebro-pedal and 
* Morphol. Jahrb., xviii. (1892) pp. 451-543 (7 pis., 2 figs.). 
