ARTOTROGUS. 



ASCIDICOLA. 



Horticutt. Soc. i. p. 3, pi. 4. figs. 27-29 ; 

 Crypt. Bot. p. 247 ; De Bary and Woronin, 

 Beit. iv. 



ARTOTRO'GUS, Boeck. A genus of 

 Entomostraca, Ord. Copepoda. Four British 

 species ; marine, living in the branchial sacs 

 of Ascidiee, or on the integument of marine 

 Invertebrata. 



BIBL. Brady, Copepoda (Ray Soc.}, iii. 

 p. 59. 



A'RUM, L. A genus of Aracese (Flow. 

 Plants). Arum macidatum, the common 

 Cuckoo-pint, has a tuberous rhizome in 

 which is produced much starch. This starch 

 is extracted in the same way as Arrow-root 

 starch is from the rhizomes of Marantaceae 

 &c., and is called Portland Arrow-root (PI. 

 46. fig. 11). See STARCH. 



AS'CARIS. A genus of Entozoa, of the 

 order Coslelmintha and family Nematoidea. 



Char. Body cylindrical, narrowed at each 

 end ; head furnished with three tubercles or 

 valves ; mouth terminal, situated between 

 the three tubercles j male with one or two 

 spicula. 



The species are very numerous, occurring 

 in all the classes of theVertebrata and doubt- 

 fully in Insects. They are most commonly 

 found in the alimentary canal. We shall 

 only notice the species met with in man. 



A. lumbricoides. The common round 

 w T orm. Inhabits the human small intes- 

 tine ; sometimes found also in that of the 

 ass, wild-boar, pig. and ox. Varies in length 

 from 3 to 15" ; is of a whitish colour ; the 

 head distinct, with the three valves (PI. 21. 

 fig. 9) finely denticulated on their inner 

 border, and each furnished near the summit 

 with a slightly projecting papilla. Female 

 larger and more common than the male. 

 Spicula two, equal. 



The recent ova are surrounded by an al- 

 buminous layer, the surface being studded 

 with numerous projecting tubercles. 



A. vermicidaris (Oxyitris verm}. The 

 human thread-worm. Found usually in the 

 rectum. White ; head frequently appearing 

 winged, or exhibiting two lateral vesicular 

 expansions (PI. 21. fig. 8 a}, produced by 

 endosmosis. Mouth round when contracted, 

 exhibiting the three lobes when expanded. 

 (Esophagus (e) containing a triquetrous 

 canal, and separated by a constriction from 

 the spherical stomach (d). Length, female 

 3 to 4-10 of an inch ; male shorter, with 

 the tail spirally coiled, much more rarely 

 met with. Anus (<?) about 1-8 from the end 

 of the body j spiculum single, with an ap- 



Uterus consisting of two lobes 

 (h) (ovaries) ; oviduct (K) opening externally 

 near the middle of the body. 



A. mystax (alata, Bell), 2 to 3 inches long, 

 as broad as a crow-quill ; common in the 

 cat, occasional in the human body. 



A. nigrovenosa, with the intestine black, 

 is found in the lungs of the frog and toad ; 

 and parthenogenesis is supposed to occur. 

 The females live in the lungs. The young 

 pass into damp earth or mud, where they 

 grow into sexual forms also producing em- 

 Dryos, which do not arrive at sexual matu- 

 rity until they reach the lungs. No males 

 are found in the lungs. 



BIBL. Dujardin, Helminthes ; Leuckart, 

 Mensch. Parasit. ii. p. 153 ; Downe, Mn. 

 Mic. Jn. 187.1, v. p. 55 (A. lumbr.) ; Cobbold, 

 Entozoa, 1879, p. 243 ; Duj. Helm. p. 178 ; 

 Leuckart, Paras., 1879, p. 128. 



ASCHEMONEL 'LA, Brady. Oneofthe 

 branching Arenaceous Foraminifera. The 

 chambers inflated, with 2 or more tubulated 

 apertures, any of which may produce a new 

 chamber. 



BIBL. H. B. Brady, Qu. Jn. Mic. 1879, 

 xix. p. 44. 



ASCIDTA, Bast. A genus of Tunicate 

 Mollusca, of the family Ascidiadae. 



Several British species. See ASCIDIAD^:. 



ASCID'IADJE. A family of Tunicate 

 Mollusca. 



Distinguished by their being single, 

 usually fixed (to foreign bodies, as sea- 

 weeds, shells, &c.), and the attachment of 

 the mantle to the test at the orifices only. 



Irregularly shaped, from half to several 

 inches long, often incrusted with stones and 

 shells, &c. ; with two orifices, one branchial 

 and pharyngeal, the other anal. British 

 genera : 



Ascidia, Bast. Test leathery ; branchial 

 orifice eight-lobed, anal six-lobed, both cir- 

 cular ; branchial sac not plaited. 



Molffula, Forbes. Globose, attached or 

 free ; test membranous, usually covered with 

 foreign matters; branchial orifice six-lobed, 

 anal four-lobed, both on contractile naked 

 tubes. 



Cynthia, Sav. Sessile ; test leathery ; 

 branchial sac plaited longitudinally; both 

 orifices four-sided. 



BIBL. Forbes and Hanley, Brit. Moll. i. 



L29 ; Gosse, Mar. Zool. ii. p. 35 ; Pascoe. 

 ol. 1880, p. 171. 



ASCIDIC'OLA, Thorell. A genus of 

 Entomostraca, Ord. Copepoda. 1 species, 

 marine. 



