94 
MR. E. C. BOUSFIELD ON THE 
Fabricius the description of a worm which he described as Nais 
quadricuspida , which appears to have some affinity with the genus 
Dero. Apparently this species has not since been observed, 
though from the description given by Fabricius (10) it seems 
sufficiently well marked *. 
Gervais (11) reclassified the Naididse, and renamed the genus 
Dero ; Urondis being the designation applied to it, apparently 
from the peculiarity of the tail. He appears to have been the 
first to remark that Muller’s figures evidently represented two 
distinct species. In common with some other writers, he 
included the Nais barbcita of Muller, in spite of the fact that the 
latter is described as having a simple truncated tail. 
CErsted (19) gave only a very short account of the genus, 
calling it Proto (Oken). 
Grube (12), whilst contributing little or nothing to our know- 
ledge of the genus, made some interesting remarks on its syste- 
matic position, and referred to two marine forms, described by 
Dujardin (8) and Huges (7) respectively, which he regarded as 
allied to Dero. Having carefully compared the papers referred 
to by Grube, I am unable to agree with his conclusion. G-rube 
also remarked on the confusion in the nomenclature, professing 
himself unable to decide the question of the origin of the name 
Proto f. It should be remarked that Grube does not mention 
having seen Dero. 
Bose (4) mentioned, under the name of Nais auricularis, a worm 
found in Carolina with a tail formed by a large tubercle, in the 
middle of which is the anus, — a description which would well 
apply to a Dero in a contracted state. 
Pennant (21), Shaw (27), Stewart (28), and Turton (30) gave 
descriptions of Nais digitata which afford no assistance in iden- 
tifying the form ; and the same may be said of a long paper by 
Houghton (13), who, having found the genus in England, instead 
* “ Nais verrucis lateralibus bifidis setosis cirris abdominal ibua et cauda 
quadrifida.” 
t The origin of this name remains unknown. CErsted attributed it to Oken, 
in whose work no trace of it is to be found ; nor is it likely that he would have 
given to one genus two different names. Another writer, in spite of Grube’s 
remark, attributed the name to him. The only feasible explanation appears 
to be that some unknown writer, between the time of Gervais and CErsted 
(t. e. 1838 and 1843), originated it in a paper which has been lost. The ‘ Nomen- 
clator Zoologicus ’ of Agassiz gives both narae^, and attributes both to Oken, but 
■evidently wrongly. The etymology is there given as cipw, casern exuo. 
