MOLLUSCS. 
433 
Vertebrates, and which parts may be called only analogous, 
serving the same purposes, without being truly identical in ele- 
mentary texture and morphological structure. He comes to the 
conclusion that the four principal classes of histological elements 
(the conjunctive or cellular tissues, the muscular, the nervous, 
and the epithelial) are really the same in both types of the animal 
kingdom, — further, that even several more specialized elements 
are also homologous, as, for example, the intercellular substance, 
the network of anastomosing cells (the cartilages being a cel- 
lular mass solidified by interposed membranes), the endothelial 
bordering membranes (as sareolcrnma and ncurolcmma), the un- 
coloured corpuscles of the blood, the ganglion-cells and nervous 
fibres and theii^ junctions, the epithelial spines, the vibratile 
cilia, the cylindrical epithelium (as chief resorbent element on 
the inner surface of the intestinal tract), the combination of ner- 
vous and epithelial elements in the organs of sense — further, the 
organs for secretion of uric acid and bile, the generative glands, 
zoosperms, and ovules. Even the branchial organs (gills) are 
said to be homologous in mollusks and vertebrates, their struc- 
ture and situation in Amphiooeus and in Tunicates being remark- 
ably similar. With regard to the heart and blood-vessels, the 
author feels not certain enough to decide whether they are 
homologous or merely analogous. The areolar or adenoid tex- 
ture, a modification of the common cellular texture, has, in 
mollusks, at present, been found in tlie orbital mass of Cephalo- 
pods only. TIjc author considers the SaljJce to be the most simple 
and original forms of mollusks, whilst the Bryozoa are much 
modified by their sessile life and composition of several indi- 
viduals. 
The existence of capillary vessels, with distinct walls, in the 
vascular system of the Gastropoda is demonstrated by injec- 
tions of coloured fluid into the heart or the larger veins, espe- 
cially in Helix pomaiia (L.) and Murex hrandaris (L.), by C. 
Wedl, Sitzgsber. Ak. Wiss. Wien, 1868, Iviii. pp. 179-201, with 
three plates. 
Contributions to Faunas. 
a. Land- and Freshwater Mollusca. 
1. Northern and Central Europe, 
The Northern species believed by various authors to be common to North 
America and Europe [circumpolar] have been enumerated and examined by 
Dr. Morch, Am. Journ. Conch, iv. p. 27 : there are 10 species, but only in 1, 
Zoogenetes harpa (Say), the author admits a specific identity. With regard 
to Z. pidchella (Mull.) = ? (Say ) and hammonis (Strom)— ? electrma 
(Gould), he concludes, from the researches of Mr. Morse, that their identity 
is improbable, and with regard to the species of Conulus, VitrtJia, and Suc- 
cinea, that it is very doubtful. [It is strange that he does not even mention 
the relation of Cionella luhrica (Mull.) to its American representative.] 
