ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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and Limnsea. No great specific value can be attached to the myology 
in these genera, and the generic value of these muscles is probably much 
less than that of the nervous, generative, or digestive systems in the 
pulmonate Mollusca generally. 
Colpodaspis pusilla.* — Mr. W. Garstang gives an account of this 
rare mollusc, a single example of which has lately been found at Plymouth. 
He adds to and somewhat modifies the original description of Sars, and 
comes to the conclusion that the Plymouth specimen presents features 
which indicate a slight advance on the organisation of those described and 
figured by Sars. It is, that is to say, 3*125 mm. long as compared with 
2*5 mm. The tentacles, the pallia! siphon and the admedian denticles 
are more differentiated, while there is perhaps some increased extension 
of the free margin of the shell. Sars was in some doubt as to whether 
Colpodaspis was really an Opisthobranchiate at all, but on this point 
Mr. Garstang has no doubt. He thinks that we may regard this genus 
as a very primitive type of a Tectibranchiate mollusc belonging indeed 
to the Cephalaspidea, but retaining in an unspecialised condition an 
unusual number of those primitive characters which the common 
ancestors of the Cephalaspidea and Notaspidea alike possessed. It 
supplies, he says, an indubitable connecting-link between these too great 
subdivisions of the Tectibranchiata, but it belongs to the group Cephalas- 
pidea in spite of the inappropriateness of the name, owing to its acqui- 
sition of pleuropodial expansions and a posterior pallial appendage — two 
associated features which are especially characteristic of that group. 
Opisthobranchs of the “ Albatross ” Expedition.-)- — Dr. E. Bergh 
gives a systematic account of the Opisthobranchs dredged by the 
“Albatross.” He describes the following new species: — JEolidia 
Jierculea , Himatella trophina , Tritonia diomedea , T. exsulans , Geitodoris 
immunda, Garganiella immaculata, Thordisa (?) dubia, Chromodoris 
Agassizii , Tridachia diomedea , Doridium purpureum , D. diomedeum , D. 
ocelligerum, Navarchus eenigmaticus. 
Hedylidae, a new Family of Nudibranchs.J — Dr. R. Bergh describes 
Hedyle Weberi g. et sp. n., from the Indian Ocean, type of a new family 
of cladohepatic Nudibranchs. It appears at present very divergent* 
Thus there are no dorsal appendages ; the body is elongated, rather 
narrow, somewhat flattened, and for more than its posterior half separate 
from the foot ; there are no mandibles ; the foot is elongated and rather 
narrow, the tail particularly long. 
Habits of Limpets.§ — Prof. J. R. Ainsworth Davis has a note on the 
homing and other habits of Limpets. It has been suggested that the 
great length of the radula of these Molluscs is to be correlated with the 
large amount of wear and tear entailed by the constant scraping of 
barnacles, &c. This view appears to be confirmed by Helcion , of which 
Laminaria constitute the chief, if not the only food, and in which the 
radula is relatively somewhat shorter. The scraping sound heard on 
rocks during warm weather is not entirely due to feeding Limpets ; 
* Proc. Zool. Soc. London, 1894 (1895) pp. 664-9 (1 pi.). 
t Bull. Mus. Comp. Zool. Harvard, xxv. (1894) pp. 1.25-233 (12 pis.). 
X Verb. K. K. Zool.-Bot. Gesellsch. Wien, xlv. (1895) pp. 4-20 (1 pi.). 
§ Nature, li. (1895) pp. 511-2. 
