ANATOMY AND CLASSIFICATION OF THE ARENICOLIDiE. 427 



figure of A. ecaudata. Dissection, moreover, revealed further 

 differences between the two species, which are especially 

 obvious in the reproductive organs (see figs. 44 and 45). It 

 is somewhat remarkable that the result of a dissection of A. 

 ecaudata has never been published/ since even a rough 

 dissection of a siugle specimen, especially in the spring of 

 the year, would have revealed so many points by which this 

 species might be at once distinguished from any other species 

 of Arenicola. The uu certainty which hangs over the 

 distinctiveness of this species, even at the present time, is 

 shown by the endeavours of some recent authors to use A. 

 Grubii, hitherto known from the Mediterranean only, as a 

 synonym for A. ecaudata. One of the objects of this paper 

 is to point out the distinguishing characters of the species, so 

 as to enable more accurate records of these forms to be made 

 than has been the case hitherto. 



The species, A. Claparedii, was founded by Levinsen 

 (1883, pp. 136 — 138), who pointed out some of the differences 

 between this Mediterranean form and the northern specimens 

 of A. marina. Specimens of Arenicola from Naples which 

 possess thirteen pairs of gills are often labelled A. marina., 

 which, howevei', does not occur in the Mediterranean. It is 

 replaced by A. Claparedii, which differs from A. marina in 

 the form of its gills, in having only five pairs of nephridia, and 

 in other ways. 



Stimpson (1856, p. 114) founded the species A. cristata 

 (A. antillensis, Liitken) upon specimens obtained in 

 Charleston Harbour. This species differs from others in the 

 richly pinnate character and smaller number of the gills, and 

 in usually possessing certain papillary processes on the tail 

 (PI. 22, fig. 1, and PI. 24, figs. 30—33). 



All specimens of Arenicola which have hitherto been 

 completely investigated and described, fall within the five 

 species meutioued above, viz. A. marina, A. cristata, A. 

 Claparedii, A. Grubii, and A. ecaudata. 



' Since this was written we have received a paper from M. Fauvel (1899) 

 in which this has been done. 



