4 LAND MOLLUSCA IN THE TROPICS chap. 



the Mollusca he obtained near St. Ann's, CuraQuo, gives a 

 lively picture of their abundance in an exceptionally favoured 

 locality : — ^ 



"Near the outskirts of the town a waste piece of ground 

 supplied me with occupation for all the time I had to spare. 

 Neither grass nor water was to be seen, the only vegetation con- 

 sisting of a few stunted cacti and still fewer acacia bushes. 

 This, however, was so rich in shells that of several species 

 enough specimens could have been collected in a few yards to 

 supply, I should suppose, all the shell cabinets in the world. . . . 

 The stones, plants, and ground were covered with Strophia uva 

 L., Tudora megaclieila^ P. and M., was in equal abundance, 

 suspended by its silk-like thread from acacia boughs, or strewed 

 thickly on the ground underneath. A Bulimulus QB. multi- 

 lineatus var. sisalensis) abounded on the smaller boughs, while 

 under masses of coral Macroceramiis inermis Gundl., Pupa par- 

 raiana d'Orb, and P. pelliicida Pfr., were abundant. In the loose 

 soil Cylindrella Raveyii Bland, Cistula i2aye?ii Bland, and a cari- 

 ous Cionella Avere so numerous that a spade would have been the 

 best instrument with which to collect them. I wasted a good 

 deal of valuable time in separating them from the soil, when by 

 simply taking away a few handfuls of mould, I might have 

 obtained a larger number of specimens. A species of Stenogyra 

 and a Succinea complete a list, all of which might have been 

 gathered from almost any square yard of ground on the hill- 

 side." 



Position of Mollusca in the Animal Kingdom. — Up to 



very recent times it was usual to regard the Mollusca as one of 

 the four subdivisions of a great family known as Malacozoa^ the 

 subdivisions being (1) Mollusca, (2) Tunicata, (3) Brachio- 

 poda, (4) Polyzoa or Bryozoa. This classification is still retained 

 in the leading modern manual on the subject.^ The progress, 

 however, of investigation leads to the belief that the Mollusca 

 are not so closely related to these other groups as such a classi- 

 fication would seem to imply. The Tunicata, for instance, 

 appear, from the whole course of their development, to occupy 



1 Quart. Journ. Conch, i. p. 371. 



2 Manuel de Conchyliologie et de Paleontologie Conchyliologique. Dr. P. 

 Fischer. Paris, 1887. 



