398 PEOP. ALLMAN ON" THE BECENT EESEABCHES 



and wMcli, under that of Dvfflugia enchelys, was subsequently de- 

 scribed by Ehrenberg, has been recently studied by Hertwig and 

 Lesser. It is provided with a firm structureless shell which does 

 not closely invest the protoplasm. It has an elongate oval form, 

 becoming wider towards the aboral pole. The shell-orifice instead 

 of lying at the end of the main axis, lies laterally and oblique to 

 it, and has its margins inflected inwards. The protoplasm-body 

 consists of a posterior homogeneous portion and an anterior more 

 granular portion. In the posterior is the nucleus with its nucleo- 

 lus, and on the boundary between the posterior and middle third, 

 lying in an equatorial plane, are the contractile vacuoles, which 

 are always three in number. The filiform and pointed pseudo- 

 podia are destitute of granules and form no anastomoses. 



Hertwig and Lesser describe a peculiar mode of cyst-formation 

 in Trinema. They have frequently found specimens of T. acinus 

 which contained in the posterior part of the shell a spherical cyst- 

 like body filled with uniform strongly refringent granules. A nu- 

 cleus with nucleolus were also generally visible in it. In some 

 cases the cyst was seen to be invested by a double membrane, appa- 

 rently analogous to the double investment observed by Hertwig 

 and Lesser in the cysts of JEuglypha alveolata (see the description 

 of this rhizopod given below). 



They have also found examples of Trinema in which the poste- 

 rior part of the shell was no longer occupied by the protoplasm- 

 body, which had the appearance of being truncated posteriorly. 

 In one of these the otherwise empty space was nearly filled by a 

 constantly rotating sphere. Whether the rotation was caused by 

 cilia or flagella, they could not ascertain ; but they believe that 

 here, as in Microgromia, the detached body was formed by a self- 

 division of the protoplasm, and is destined to become liberated as 

 a swarm-spore. 



Like many other freshwater Thalamophora, two individuals 

 of Trinema acinus are often found united to one another by their 

 pseudopodial orifices. No change has been noticed as the result 

 of this union, which has probably nothing to do with reproduction. 



Claparede and Lachmann consider the Euglypha pleurostoma 

 of Carter as identical with Dujardin's Trinema acinus ; and this 

 view is accepted by F. E. Schulze, who attributes to Trinema a 

 sculptured shell like that of Euglypha. With this identification 

 Hertwig and Lesser do not agree. They believe that Carter has 

 rightly referred his rhizopod to the Euglyphce. 



