NOTICES OF NEW BOOKS. 159 



seized a smaller specimen, 21 mm. in diameter, in the aquarium. 

 The small one was making efforts to escape, but was followed by the 

 large one. The small one crept into a corner of the tank, whereupon 

 the large one imprisoned it in the corner with spines and tube-feet, 

 and "sat" upon it for several hours until it had sheared off all except 

 a few of the spines and tube-feet of the upper pole of the victim. So 

 completely had this shearing process been carried out that not only 

 was the test laid bare, but the rounded tubercles to which the spines 

 articulate were in many cases scraped away. (I pointed out in my 

 paper that the periostracum and rugosities of mollusc shells were 

 similarly scraped flat.) The few spines left upon the upper surface 

 had been broken off about their middles. The small Sea-Urchin was 

 now rescued from its oppressor; but next morning I found that 

 another Sea-Urchin, 23 mm. in diameter, had taken advantage of the 

 helplessness of the victim to turn it over and scrape away most of 

 the spine and tube-feet of the oral surface, the mouth -membrane 

 being also bitten in several places. No spines could be found on the 

 floor of the tank, and it may therefore be concluded that in both 

 instances these had actually been swallowed. The small Sea-Urchin 

 was now removed for safety to an empty tank ; but it had been so 

 badly damaged that it would neither eat nor move, but clung motion- 

 less to the vertical face of a rock with its few remaining tube-feet. — 

 H. N. Milligan. 



NOTICES OE NEW BOOKS. 



The British Freshivater Bhizopoda and Heliozoa. By James Cash 

 and George Herbert Wailes, E.L.S., assisted by John 

 Hopkinson, E.L.S. Vol. III. Bhizopoda, Part III. London : 

 Bay Society. 1915. 12s. Qd. net. 

 For this third volume of the Bay Society's monograph of our 

 Freshwater Bhizopoda, which will be completed, we are told, by 

 a fourth, Mr. G. H. Wailes is largely responsible, since the regretted 

 death of the late James Cash left the work unfinished ; his descrip- 

 tions and records of localities have, however, been utilised, his name 

 being appended to the local records, and some drawings by him are 

 reproduced in the very full series of plates which, twenty-four in all, 

 terminate the volume. Most are in black and white, but eight are 

 coloured, and the text is also illustrated by line drawings of details, 

 the degree of magnification being given in both cases. The groups 

 dealt with include the families of Euglyphina, Gromiina, and Amphi- 



