Marine Animal Forms in Fresh Water. 61 



only the scanty division of the iMcrostoma {Limuhis), the most 

 northern of whieh occurs near Boston. 



Of tlie essentially a([uatic classes (or subclasses, according to 

 the differences of system) of animals, we find that eleven, namely 

 the Polycystinea?, Anthozoa, Acalephre, Ctenophora, Siphono- 

 phora, Echinoderniata, Tunicata, Braehiopoda, Pteropoda, Iletc- 

 ropoda* and Cephalopoda are exclusively marine, and the same 

 number, namely, besides the forms already referred to, the Infu- 

 soria and Khizopoda, the Ilydroid polypes. Rotatoria, Bryozoa, 

 Turbcllaria, and Annelida, arc common to both media, amongst 

 which, however, the very numerous sections are j)urely marine 

 (Sertularina, Bryozoa Stelmatopodaf, and the numerous, very 

 hiirhly developed order of the Annulida), whilst the sections 

 proper to the fresh water are less rich in species, like the 

 freshwater Polypes and Bryozoa [Hijdrina and Bryozoa Lopho- 

 poda) and the Planaria in the most restricted sense. 



The Batrachia furnish the only example of a class of animals 

 whieh is entirely wanting in the sea, and yet they are water- 

 breatiiers, at all events teuiporarily : we are acquainted with ma- 

 rine Tortoises, marine Lizards (Darwin's Ambh/rJnjnchus cristatus 

 upon the Galapagos Islands), and marine Snakes {Hy drop his), 

 besides the notorious Norwegio-American one, but, in spite of 

 Seba and Schiller's ' Taucher', not a single Sea Toad or Sea Newt. 

 Of the strictly air-breathing classes, lastlj^, certain representatives 

 live constantly in the sea ; of the Birds and Insects only a few 

 venture temporarily into and under the water, both fresh and 

 salt, but live essentially above its surface J ; amongst Insects, we 

 have here especially the small, apterous, Carabideous Beetle 



[* The author has previously rejjardcd the Ileteropoda as formino- a 

 portion of the class Gasteropoda. — Tuansl.] 



t According to Duinortier and Van Benedcn, however, the freshwater 

 genus Palndicella belonj^s to this group. — [According to Professor Allman 

 (' Monograj)!! of the Freshwater Polyzoa,' Ray Society, 185(j), both Pain- 

 dicella and Urnatella, although freshwater genera, belong to the group 

 above mentioned ; whilst ou the other hand, the marine genus PediceUina 

 appears to have a bilateral lophophore, wliich would cause its location 

 amongst the fresl.watcr forms. Fredericella also, a freshwater genus, pos- 

 sesses a funnel-shaped loidiojiliore. Professor Allman's classification, in 

 which the two orders of Polyzoa are distinguished by the ])resence or 

 absence of an epistome, or lobe in the vicinity of the mouth, docs not get 



rid of this appearance of marine forms in fresh water and vice versa.- 



Transl.] 



\X The author here seems to have forgotten the existence of whole fami- 

 lies of Beetles and Bugs, which live habitually beneath the surface of the 

 fresh water, whilst the larv;B of many of the former are even adaiited to 

 aquatic res])iration. The larvic of a great proportion of the Xeuroptera 

 also are strictly aquatic, and those of many Diptera live in water, although 

 most of them breathe air. — Transl.] " 



