ON THE ANGUILLULIDA. 111 
genus Anguillula, he has now, in his more recent * Revision der N ematoden,’ transferred 
to the genus Isacis of Lespés; whilst he includes, as subsections of the former genus, 
certain other of these parasitie forms, mostly discovered by Dr. Leidy, of Philadelphia, 
and placed by him, rightly enough, in distinct genera—Streptostoma, Thelastoma, and 
Hystrignathus. 
For many of the descriptions and references concerning old species placed in this and 
other genera I have freely availed myself of Diesing’s admirable work. 
1. A. AOETT, Ehrenberg. (Pl. X. figs. 594-59c.) 
Borellus, Obs. Microscop. Centur. 7, 1656. 
Power, Microsc. Obs. 38. 
Hook, Microsc. 1. 2, tab. i. 
Joblot, Obs. Micr. i. 2, tab. i. 
Leeuwenhoek, Phil. Trans. 1676, p. 656. 
Cellius, apud Bakerum, ii. 250 (vivipara). 
Backer, Micr. tab. x. 8, 9; Micr. Expl. 81, tab. v. 10. 
Fränkische Samml. iv. 277, figs. g-o. 
Goeze, Naturf. i. St. 1-53, et xviii. St. 38, tab. iii. 12-19.—Idem in Bonnet’s Organis. Kórp. 59. 
Spallanzani, Opus. Phys. i. 83. 
Rozier, Anguille du Vinaigre, Obs. 1775, Mars, tab. i. fig. 5; 1776, Janv., 51, et Mars, 382. 
Essig- Aelchen, Martini, Allgem. Gesch. d. Nat. i. 412; Beschäft. Berlin. Gesellsch. i. 342. 
Chaos redivivum, Linné, Syst. Nat. 1326 (aceti). 
Vibrio anguillula, a. Anguillula aceti, Müller, Anim. Infus. 63, tab. ix. 1-11.—1dem, in Naturf. xix. St. 162. 
Vibrio aceti, Bory, in Encycl. Méth. 1824, p. 788, tab. iv. 16.—Dugés, in Ann. des Sc. Nat.ix. 225, tab. xlvii. 
2,19, 32 9, et xlviii. 44-50 4,51 (in copulä).—De Blainville, in Dict. des Sc. Nat. lvii. 573 et lviii. 70. 
Rhabditis aceti, Dujardin, Hist. Nat. des Helminthes, 242. 
Czernay, Monogr. d. Essigälch. mit kol. Kpft. Moskau, 1849.—Idem, Bullet. de Moscou, xxii. (1849) 
232-256, tab. vi. (cum anatom. et de evolut.). 
Anguillula aceti, Ehrenberg, Infusionsth. 82. 
Leidy, in Proc. Acad. Philad. viii. (1856) 48. 
Hogg, Pop. Sc. Review, Jan. 1863, p. 216, pl. x. 
Diesing, Syst. Helminth. ii. p.128; et Sitzungsb. ais. Akad., Bd. xlii., No. 28, p. 627. 
Female (size very variable). Length 45^, breadth 355”. | 
External Characters.—Body white, much obscured by colourless granules within 
integument ; long and narrow, tapering very much posteriorly, and terminating in a long 
pointed extremity. Head rounded, unarmed. Integument thin, showing no striz. 
Pharyngeal cavity very minute, cup-shaped. (Esophagus 4th of total length, having a 
rounded swelling at termination, containing valvular apparatus. Intestine covered with 
Coarse colourless granules; no sort of tessellation. Anus sg” from posterior extremity. 
Vulva somewhat posterior to middle of body. Uterus unsymmetrical. Small floating 
Jlaud-cells numerous in cavity of body. 
Male. Length 3", breadth sls 
Esophagus 4th of total length. Anus „15” from posterior extremity. Spicules narrow, 
having à double curve, 14 long. Accessory piece about lrd as long as spicules, rather 
thick externally, but expanding inwards into a thinner fan-shaped portion. 
