Arenicola ecaudata 133 



Arenieola ecaudata, imrtim — 



Ives, Proc. Acad. Nat. Sci. Tbilad. 1890 (1891), p. 74. 



Arenicola boeckii — 



liathkc, Nova Acta Acad. K. Leop.-Car., xx (1840), p. 181, tab. viii, figs. 

 19-22 (Trondhjeni). 



Arenieola bucci — 



Hanna, Proc. l^elfast Natur. Field Club, scr. 2, iv (1898), p. 42.0 (Antrim). 



Arenicola branchialis, partim — 



Fauvel, Proc. 4th Intern. Congr. Zool. (1899), p. 229. 



Johnston, Catal. Worms Erit. Mus., p. 231. 



MarenzeUer, Zool. Jahrb. Abt. Syst., iii (1888), p. i:?. 



Mesnil, Bull. Sci. France Belg., xxx (1897), p. 163. 



Michaelsen, J.-B. Komm. Wiss. Unters. Kiel, N.F., ii (1896), p. 136. 



Saint-Josejjh, Ann. Sci. Nat. Zool., ser. 8, v (1898), p. 391. 



Lumbricus marinus, another sj)ccies — 



DahjeU, Powers Creator, ii (1853), p. 137, pi. xix, figs. 4-7 (Shetland). 



Clymenides eeaudatus — 



Mesnil, Bull. Sci. France Belg., xxx. p. 152 (St. Martin). 



Ecaudate Arenicola, with first gill ou the sixteenth ^ ehaetiferous 

 segment ; thirteen pairs of nepliridia, which open ou the fifth to the 

 seventeenth segments ; gonads large, each gonad is produced, in the 

 mature male, into one or more thin reniform outgrowths, and, in 

 the mature female, into numerous digitiform or flattened processes. 



Historical Account. — Johnston defined his new species in the 

 following terms: — "A. ecaudata. Branchial tufts more than twenty- 

 pairs; the first fourteen or fifteen pairs of feet ahranchial, tail none." 

 There was, in the minds of some authors, considerable doubt as to 

 the validity of this species, which was confused with A. f/rubii 

 (= hmnchialis). Until 1898 there was no published reference to 

 the internal organs of A. ccaudafa; then appeared, in close succession, 

 the observations of l)rs. (Jamble and Ashworth, and Profs. Mesnil 

 and Fauvel, which finally dispelled all doubts regarding the autonomy 

 of this species. 



To Trof. Mesnil (1897) we owe the first description of the post- 

 larval stages, which, however, belie\'ing them to belong to the 

 genus Clymenides, he designated C. ecaudahis. Prof. Fauvel reared 

 an example of " C. eeaudatus " into a y^oung Arenicola ecaudata, and 

 thus demonstrated then- identity. 



' The first gill is often small, and in about twenty per cent, of the specimens 

 examined was wanting. 



