chap, xxiv.] AXIAL DUPLICITY : INVERTEBRATES. 565 



Oligoch^ta. 



Allolobophora longa : specimen represented as bearing a second 

 head on the right side of the first segment behind the peristomium. 

 The second head is represented with prostomium, peristomium and one 

 more segment which rests on the peristomium of the normal body. 

 Friend, H., Science-Gossip, 1892, July, p. lQl,fig. 



Ctenodrilus monostylos : double tail ; in many hundreds 

 examined, three cases seen, Zeppelin, Z.f iv. Z., 1883, xxxix. p. 621, 

 PI. 36, figs. 18 and 19. 



Lumbriculus variegatus : similar cases, von Bulow, Arch. f. 

 Naturg., 1883, xlix. p. 94. 



Acanthodrilus sp. : case of two tails arising from a much thicker 

 anterior portion. Such worms were believed or alleged to be common 

 in a par-ticular district in New Zealand. Kirk, T. W., Trans. N. Zeal. 

 Inst., xix. p. 64, PI. 



Earthworms generally, belonging to genera Lumbricus, or 

 Allolobophora : cases of double tail recorded, as follows : Robertson, 

 C, Q. J. M. S., 1867, p. 157, fig.] Horst, Notes Leyd. Mus., vn. p. 42; 

 Thompson, W., Zool., xi. p. 4001 ; Bell, F. Jeffrey (2 cases), Ann. & 

 Mag. N. H., 1885 (2), p. 475, fig.; 'Friend, H., Sci.-Gossip, 1892, p. 

 108, figs. ; Marsh, C. D., Aimer. Nat., xxiv. 1890, p. 373; Fitch, A., 

 Eighth Rep. upon Insects of State of N. Y., Append., 1865, p. 204 [from 

 Andrews, I.e.]; Terat. Cat. Mus. Coll. Surg., 1872, No. 20. Breese, 

 West Kent N. II. S., 1871; Broome, Trans. N. H. S. Glasgow, 1888, p. 

 203 ; Foster, Hull. Sci. Clnb, 1891 ; [the last three quoted from Friend, 

 Nature, 1893 (1), p. 397]; Collin, A., Naturw. Wochens., 1891, No. 12, 

 figs. I have also a specimen with two nearly symmeti'ical tails kindly 

 sent by Mr W. B. Benham. 



Arthropoda. 



Three cases. 

 '878. Chironomus (Gnat): larva with two heads, duplicity beginning 

 from the 5th segment behind the head [important details given, q. v.]. 

 Weyenbergh, H., Stet. ent. Ztg., 1873, xxxiv. p. 452, fig. 



879. Euscorpius germanicus (Scorpion) : tail double from 4th prae- 

 abdominal segment [figure represents each abdomen with one segment 

 too few, presumably an error]. Pavesi, P., Rend. R. 1st. Lomb., S. il, 

 xiv*. 1881, p. 329, fig. 



880. [Scorpio africanus :] specimen with two tails. Seba, Rerum 

 Naturalium Thesaurus, 1734, i. p. 112, PI. lxx. fig. 3. This example 

 was kindly sent me by Mr R. I. Pocock, who tells me that the figure 

 shews the animal to be of the species named. 



Cestoda. 



Conditions, perhaps akin to duplicity, have been seen to occur 

 under three forms. 



881. Taenia ccenurus : specimen whose head had 6 suckers instead of 

 4, and 32 hooks instead of 28. Proglottides were 3-sided prisms, in 

 section triangular. Longitudinal vessels 6 instead of 4, two being in 

 each angle. Absolute size of head greater than normal. This abnormal 



