ON THE ORGANIZATION OF THE GENUS GREGARINA OF DUFOUR. 23? 



The older Gregarina; when distended with granular contents, frequently arc quite mo- 

 tionless. 



Among the Gregarina of twenty or thirty different insects and myriapoda, I have pre- 

 served notes only of seven, which I append to this communication. 



CHARACTER OF THE GENUS. 



Gregarina, Dufour. 



Dufour, An. d. Sc. Nat. T. 8, 182G. 



Gregarina. — Dufour, An.d. Sc. Nat., 1S28; Hammerschmidt, Isis von Oken, 1838; Sie- 

 bold, Beitr. z., Naturg. d. wirbelloscn Thiere, 1839; Kblliker, Zeits. f. wiss. Botanik, 1845; 

 Zeits, f. wiss. Zoologie, 1848; llcnlc, Midler's Archiv, 181"); Frantzius, Obscrvat, quaxlam 

 de Gregarinis, 1S4G; Archiv f. Naturgcs. 1848; Stein, Muller's Archiv, 1848. 



Clepsedrina, Rhizinia, Pyxinia, Bullulina, Hammerschmidt, Isis von Oken, 1838. 



Sporadina, Stylorhynchus, Actinoccphalus, Frantzius, Archiv f. Naturgeschichte, 1818. 



Boily consisting of two sacs connected together, composed of amorphous memhrane, and filled with granular 

 contents. Anterior or cephalic sac much the smaller. Posterior sac lined with a second tunic, marked with ex- 

 ceedingly regular, parallel, longitudinal lines. Granular mass of the posterior sac containing one or two globular, 

 transparent corpuscles. 



1. Gregarina Juli marginati. 



Gregarina larvata, Leidy, I'roc. Acad. Nat. Sci., vol. iv., p. 232. 



Opaque, white, cylindrical or fusiform, narrowed posteriorly, frequently considerably dilated at the anterior third. 



Anterior or cephalic sac small, oblate spheroidal, received about one-half into a depression of the inferior 

 cell, surmounted by a papillary elevation or thickening of the parietal integument, which often appears as if there 

 were outlines of a canal or communication with the interior in it; interior filled with a finely granular mass) 

 resembling ag aggregation of oil globules; granules measuring from 1.15,000th to 1.7,500th of an inch. 



Posterior sac, elongated, cylindrical, or fusiform, obtuse posteriorly; interiorly filled with a granular matter like 

 that of the cephalic sac, rendering the larger or older individuals opaque from its quantity, and one or two large, 

 globular, transparent, homogeneous corpuscles, containing a fine, granular matter, and a round, granular, or trans- 

 parent nuclear body, in older individuals with one or two nucleoli ; interior of the parietal integument invested 

 with delicate and exceedingly regular parallel lines, about the 1.9375th of an inch apart. 



Whole length of animal from the 1.200th to the 1.30th of an inch. 



Cephalic sac of largest individual, 1.800th in. long; L. 616th in. broad; of smallest 1.1232d in. long. 



Breadth of posterior sac, from the 1.830th in. to the 1. 1 1 Ith in. 



Corpuscle of the posterior sac, in the larger individuals, the 1.375th in. in diameter; its nucleus the 1.907th 

 in.; the nucleolus the 1.1606th in. 



Habitation. — Found in considerable numbers in the provcntriculus of Julus marginatum, 



in about two-thirds of the animals examined. 



Movements. — This is the most active species which I have ever observed. Individuals 

 are found, generally those of largest size, which arc frequently motionless. The move- 

 ments consist of a contraction, more or less extensive, of the posterior sac. This occurs 

 sometimes to such an extent, that the body will be so narrowed that the parietes come in 

 contact, and the granular contents are divided into two portions, one anterior and the other 

 posterior to the constriction. It will also bend into a sigmoid posture, or roll itself into :i 

 helix. At times the cephalic sac is totally drawn within the posterior, and again projected. 

 vol. x. — 47 



