22 ILLINOIS BIOLOGICAL MONOGRAPHS [22 



DISCUSSION OF THE NEW FAMILY LECUDINIDAE 



The type genus of this family, Lecundina was named by Mingazzini 

 in 1891. Two years later Leger, working independently, designated a 

 new genus Doliocystis for the species described by Mingazzini. The 

 earlier work has been overlooked by subsequent workers while the name 

 used by Leger has come into frequent usage, the genus being raised to 

 family rank (Doliocystidae) by Labbe, in 1899. 



In Table I of Chapter II, is shown the intermediate position of the family 

 Lecudinidae and the somewhat related family, the Polyrhabdinidae. The 

 Lecudinidae are related to the Tribe Acephalina, for they are non-septate, 

 there being but one division in the body at all stages of development. 



All the members of the Tribe Cephalina, on the other hand, are char- 

 acterized by the presence of a septum, which divides the body into a 

 protomerite and deutomerite, if not in the adult, at least in the trophic 

 stages of development. When the septum is absent from the adult, it is 

 clearly a degenerative rather than a rudimentary character, all other 

 generic features conforming to the type. 



(Cf. Schneideria, Sphaerocystis, Rhopalonia, Gamocystis.) 



The Lecudinidae, however, possess only the epimeritic demarkation 

 from the rest of the body, and when this structure disappears, the body is 

 unilocular. Leger (1893) remarks: 



... la gre"garine pr6sente toujours deux segments: le segment intra-cellulaire ou 

 epimlrite, et le segment extra-cellulaire dans lequel s'est porte le noyau. C'est done seulement 

 ce moment que la gre"garine se montre" comme une veritable dicystide"e. . . . les jeunes 

 individus abandonnent leur tpimtrite et deviennent libres dans 1'intestin, pr&sentant a lors 

 toutes les apparences de veritable Monocystis .... 



In the type species, Lecudina pellucida (Koll.) Ming., there is a differ- 

 entiation in the protoplasm of the anterior end (what would be the pro- 

 tomerite in polycystids) from that of the remainder of the body. This 

 was illustrated by Kolliker (my fig. 126) but not mentioned by Leger in 

 1893. Brasil (1909) illustrates this differentiation clearly in both tropho- 

 zoite and sporont (my figs. 134 and 135). 



If normally present, and I have no doubt that it is but often not 

 mentioned or discovered, this character is an important one in assigning 

 the family in question to an intermediate position between the monocystids 

 and the polycystids. 



In its cyst-formation and spore type, the family follows the polycystid 

 type. 



After the above had been written, this statement from Minchin (1903) 

 was found: 



The possession of an epimerite is a feature is used for classifying which the Gregarines, 

 and the legion Eugregarinae is separated into the two sub-orders Cephalina and Acephalina, 

 according to the presence or absence of this appendage. As a general rule the forms which 



