CHAETOPODA. 611 



development; aquatic; limicolous or terrestrial 1 . Aphanoneura (= Aeolosomidae), 

 Naidomorpha, Chaetogastridae, Discodrilidae ( Branchiobdella)*> Enchytraeidae, 

 Tubifiddae, &c., Lumbriddae, &c. 



III. Chaetopoda ectopajasitica, ante, p. 609. 



IV. Archi-Chaetopoda, ante, pp. 609-10. 



For lit. of Oligochaeta, see pp. 200, 208, 212 ; add. Stole, ' Naidomorpha,' Z. A. 

 ix. 1886; Benham, 'Studies,' &c. } Q. J. M. xxvii. (i), 1886. 



Polychaeta, Ehlers, Borstenwiirmer, Leipzig, 1863-68; Claparede, Annelides 

 Che'topodes du Golfe de Naples, Geneva, 1868 ; Supplement, 1870 ; Id. Recherches 

 sur la Structure des Annelides Sedentaires, 1873 (or in Me'moires de la Societe* de 

 Physique de Geneve, vols. xix., xx., xxii.) ; Marion and Bobretzky, Annelides du 

 Golfe de Marseilles, A. Sc. N. (6), ii. 1875 ; Marenzeller, Adriatic Annelids, SB. 

 Akad. Wien, Ixix. 1874, Ixxii. 1875, Ixxxix. 1884, all Abth. i; Mclntosh, Anne- 

 lids of Challenger Exped., Challenger Reports, xii. 1885; Langerhans, Wurmfauna 

 von Madeira, Z. W. Z. xxxii. 1879; xxxiii. 1880; xxxiv. 1881 ; xl. 1884. 



De Quatrefages, Histoire Nat. des Annele's, 2 vols. with atlas, Paris, 1865. 



Polynoe clava, Bourne (A. G.), Tr. L, S. ii. pt. 7, 1883 ; P. drrata, Kallenbach 

 (Kieler dissert.), Jena, 1883. Oligognathus Bonelliae, Spengel, Mitth. Zool. Stat. 



1 The Oligochaeta were formerly divided into the Terricola and the Limicola. The Terricola 

 were distinguished by the presence of a sub-neural blood-vessel, a capillary network surrounding the 

 nephridia, a typhlosole, the presence of nephridia in the same somites as the sexual ducts. But the 

 discovery of new forms and the fact that in the Limicola the nephridia of the genital somites atrophy 

 when the genital ducts develope, have broken down the division. See the account of Lumbricus, 

 pp. 196-212. 



2 Branchiobdella, which is usually classed among Hirudinea, is placed by Vejdovsky among 

 Oligochaeta. There is one species, B- varians (Voigt), with several local varieties. It is small 

 (3-12 mm.), parasitic on Astacus, but not in England. Of the eight middle somites, seven are 

 formed of two rings, one large, one small. There is a posterior sucker formed by the modification 

 of post-anal somites. The coelome is roomy and divided by transverse septa. Large cutaneous 

 glands open on the head and sucker, and secrete a sticky adhesive substance. The sub-oesophageal 

 ganglion corresponds to four embryonic ganglia, and there is concentration of ganglia again at the 

 posterior extremity of the cord. There is a pair of large stomatogastric ganglia as in Oligochaeta. 

 The ganglion cells form prominent masses as in Leeches. There are tactile setae on the head. The 

 buccal cavity is armed with two opposing chitinoid teeth, one dorsal, one ventral. Glands open into 

 it. The anus is dorsal. Chloragogen cells (p. 202) are present. There is a dorsal and ventral 

 blood-vessel connected by seven transverse anastomoses, five anterior, two posterior, and an intestinal 

 sinus. The blood-system is closed, the blood colourless in young, yellow or red in adult, specimens. 

 There are two pairs of nephridia, one posterior, the other anterior ; and the members of the latter 

 pair belong to different but successive somites. Testes and ovaries appear to be derived from 

 peritoneal cells ; the former are attached to the posterior aspect of a septum, the latter to the sides of 

 the intestine in the second somite behind the testes. The vas deferens is composed of two ciliated 

 funnels and ducts, which perforate a septum, unite, open into a glandular tube some distance from 

 its end. A median and protrusible penis is continuous with the gland-tube. The oviducts are 

 represented by two slits situated each on the apex of a papilla and leading into a short wide lube. 

 The genital products appear to be set free and to ripen in the coelome. There is a median azygos 

 spermatheca in the testicular somite. The ova are laid singly in a delicate case, which is attached 

 by a pedicle to the Astacus harbouring the worm. 



Voigt, Arb. Zool. Zoot. Inst. Wurzburg, vii. 1885 ; viii. 1886. Dorner, Z. W. Z. xv. 1865. 

 Lemoine, French Association for Advancement of Science, Reims, 1880. Development ', Salensky, 

 Archives de Biol. vi. Pt. i. 1885. 



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