The Cambridge natural history, Vol. 03 (of 10)

The general plan of classification adopted in this work is not that of any single authority. It has been thought better to adopt the views of recognised leading specialists in t...

Class Order Sub-order Section { OCTOPODA (p. 382). { { Phragmophora (p. 386). { =Dibranchiata= { { Sepiophora (p. 388). { { { { { DECAPODA { Chondrophora { _Myopsidae_ (p. 389)....

It is the generally accepted opinion among men of science that all life originated in the sea. Not that all parts of the sea are equally favourable to the development of forms o...

The majority of the Land Mollusca are probably more sensitive than is usually believed. The humidity of the air must affect the surface of their skin to a considerable extent. E...

The juicy flesh and defenceless condition of many of the Mollusca make them the favourite food and often the easy prey of a host of enemies besides man. Gulls are especially par...

The employment of shells as a medium of exchange was exceedingly common amongst uncivilised tribes in all parts of the world, and has by no means yet become obsolete. One of the...

Reproduction in the Mollusca invariably takes place by means of eggs, which, after being developed in the ovary of the female, are fertilised by the spermatozoa of the male. As...

The principle of respiration is the same in the Mollusca as in all other animals. The blood is purified by being brought, in successive instalments, into contact with pure air o...

Tactile organs, although occurring in some of the Mollusca, do not appear to attain special or marked development, except in a few cases. The whole surface of the skin, and part...

The digestive tract, or, as it is often termed, the alimentary canal or gut, is a very important feature of the Mollusca. It may be regarded as consisting of the following parts...

The popular names of ‘shells,’ ‘shell-fish,’ and the like, as commonly applied to the Mollusca, the intrinsic beauty and grace of the shells themselves, resulting in the passion...

The Mollusca afford specially valuable evidence on problems of geographical distribution. This fact is largely due to their extreme susceptibility to any change in the condition...

Regarded as a whole, the Ethiopian is poorest in land Mollusca of all the tropical regions. And yet its characteristics are very remarkable. The entire _Achatina_ group is pecul...

Marine Mollusca may be divided roughly into Pelagic and non-Pelagic genera. To the former division belong all Pteropoda and Heteropoda, and a large number of Cephalopoda, togeth...

The Cephalopoda present a complete contrast to the majority of the Mollusca in habits and in many points of organisation. In their power of rapid movement and their means of pro...

=Sub-order 1.= =Polyplacophora= (Chitons).--Foot co-extensive with ventral surface of the body, dorsum with eight transverse plates, articulated (except in _Chitonellus_), a row...

Visceral loop not twisted (except in _Actaeon_) in a figure of 8 (Euthyneurous type, p. 203), auricle usually behind the ventricle, ctenidium often replaced by secondary branchi...

The Scaphopoda form a small but very distinct class, whose organisation is decidedly of a low type. The body is usually slightly curved, the concave side being the dorsal; muscl...

The group Brachiopoda owes its chief interest to the immense variety and great antiquity of its fossil forms. Whereas at the present time the number of extant species amounts to...

The wide distribution and vast abundance of the Brachiopoda throughout the whole series of geological formations make this group of especial importance to the student of the pas...