v GEOGRAPHICAL DISTRIBUTION LAND FORMS I I 7 



tozoa. The whole process only lasted a few minutes. When all 

 the spermatozoa had apparently been given out, the female was 

 seen to protrude her head from the sand ; she then passed to 

 the side of the vessel and deposited a group of eggs about three 

 inches distant from the spermatozoa. 



With only a few exceptions Nemertines are oviparous. Prosor- 

 hochmus claparedii, Tetrastemtna obscurum, and Monopora vivipara 

 have been observed to contain embryos at certain times of the 

 year. In other forms the eggs are laid when ripe, and develop- 

 ment takes place subsequently to their deposition. 



Geographical Distribution. Nemertines have been found in 

 all seas from the arctic to the equatorial regions. Many forms 

 are found in the British Isles both between tide-marks and also 

 at greater depths around our coasts. Some genera seem to 

 be confined to warm climates and others to cold ; while others 

 appear to be indifferent to climate, and to subsist equally well 

 under very various degrees of temperature. So far as is known, 

 the land forms are all indigenous to warm countries. 



Land Forms. Land forms, which occur on or in moist earth 

 under stones or decaying vegetable matter, have been discovered 

 and described by Semper, 1 Willemoes-Suhm, 1 and von Graff. 1 



The species found by Semper, and called by him Geonemertes 

 palaensis, lives under damp leaves and the roots of trees on 

 Pelew Island in the North Pacific. It is about 2 inches long, 

 of a reddish-white colour, with narrow, brownish-black, longi- 

 tudinal stripes on its dorsal surface. It possesses six eyes and 

 very small cephalic slits and cerebral organs. The proboscis is 

 armed, and opens by the mouth instead of by a special pore. 



The same peculiarity as to the opening of the proboscis is 

 found in Geonemertes chalicophora, discovered by von Graff in pots 

 of Coryplia australis in the palm-house at Frankfurt-on-Main. He 

 found specimens on and beneath the surface of the earth. As it was' 

 only found in pots in which this Australian plant was growing, von 

 Graff thought it almost certain that it was a native of Australia. 

 Those found below the surface of the earth were surrounded by a 

 transparent tube in which particles of earth were embedded. The 

 animal is small, only about two-fifths of an inch in length. The 

 colour is milk-white, with a small quantity of red pigment ante- 

 riorly : there are four eyes, and the cephalic slits are absent. 

 1 References to these works are given on p. 101. 



