Miscellaneous . 317 



marked with exceedingly regular, delicate, longitudinal, parallel lines 

 about 1-93 75th in. apart, apparently muscular in character. 



Length from i-160th to l-30th m., by l-830th to 1-1 11th in. in 

 breadth. 



Hab. Found in numbers of from half a dozen to over a hundred, 

 in the ventriculus of Julus marginatus. 



Gregarina is probably the larva condition of some more perfect 

 animal, but in the 116 individuals oi Julus which I have examined, 

 I have not been able to detect any form which could be derivable from 

 it. Creplin doubts its animality*. When I first discovered this 

 body, thinking it to be a larva, I did not examine it carefully, and it 

 was not until some time afterward, when, being desirous of ascertain- 

 ing its true nature, upon examining some fresh specimens beneath 

 the microscope, I detected movements of an animal character, and this 

 led me to seek for muscular structure, which resulted in the discovery 

 of the longitudinal lines of the inferior cell. These escaped the ob- 

 servation of Siebold, for he says, *'^Nach meineBeobachtungen bestehen 

 die Gregarinen aus einer harten glatten den Eihiillen der Insekten-Eier 

 iihnlichen Hautf ." The movements of the animal are exceedingly 

 sluggish, and consist of a very slow bending in any direction of any 

 part of the inferior cell, most usually above the middle, rarely at the 

 inferior extremity, but most frequently near the superior cell which 

 is entirely passive. The superior cell is also frequently drawn or con- 

 tracted within the inferior, and again protruded by the contraction of 

 the latter, and the propulsion of the granular contents against it. 

 The inferior ceil is also frequently, more especially in younger indi- 

 viduals, intus-suscepted within itself through a partial contraction, and 

 again relieved by a general contraction of the cell-wall. 



In the state in which Gregarina is found, it would probably hold 

 a rank between the Trematoda and Trichina^ the lowest of the Isie- 

 matoidea. — Proceedings of the Academy of Natural Sciences of Phi- 

 ladelphia, vol. iv. p. 229. 



On the mouthless Acari which have been formed into the genus 

 Ilypopus. By F. Dujardin. 



Degeer, Hermann and Geoffroy found vipon various insects some 

 very small parasitical mites, to which they gave the name of Acarus 

 muscarum and Acarus spinitarsus ; they were not, however, able to 

 study them on account of their extreme minuteness. Duges, who 

 examined a single one only, constituted the genus Ilypopus of it, 

 characterized by a sucker, provided with two rigid bristles, but re- 

 gretting at the same time that he had not sufficiently studied it. 

 Since that period, M. Leon Dufour has made known two other 

 species, and M. Gervais has described a fifth species ; but he has 

 mistaken the projecting lines resulting from the contiguity of the 

 hips for a nervous system. M. Koch in Germany has also described 

 two other species of them, but without making any attempt at inves- 

 tigating their organization. W. Dujardin, who in 1842 described, 



* Nachtrage zu Gurlt's Verzeichniss der Thiere bei welehen Entozoen 

 gefunden worden sind. Wiegniann's Archiv, 1846, 1 Band, S. 157. 

 t Wiegmann's Archiv, 1838, 2 Band, S. 308. 



