Arenicola ecaudata 133 



Arenicola ecaudata, partim 



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



Arenicola boeckii 



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

 19-22 (Trondhjeni). 



Arenicola bucci 



Hanna, Proc. Belfast Natur. Field Club, ser. 2, iv (1898), p. 425 (Antrim). 



Arenicola branchialis, partim 



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



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



Marenzeller, Zool. Jahrb. Abt. Syst., iii (1888), p. 13. 



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



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



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



Ijumbricus marinus, another species 



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



Clymenides ecaudatus 



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



Ecaudate Arenicola, with first gill on the sixteenth l chaetiferous 

 segment ; thirteen pairs of nephridia, which open on 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. 



HISTOKICAL 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 abranchial, tail none." 

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

 the validity of this species, which was confused with A. cjrubii 

 ( branchialis). Until 1898 there was no published reference to 

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

 the observations of Drs. Gamble and Ash worth, and Profs. Mesnil 

 and Fauvel, which finally dispelled all doubts regarding the autonomy 

 of this species. 



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

 larval stages, which, however, believing them to belong to the 

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

 an example of" C. ecaudatus" into a young Arenicola ecaudata, and 

 thus demonstrated their identity. 



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

 examined was wanting. 



