NATUBIL HrSTORT OF THE OEJiUS DERO. 



95 



o£ observing it for himself, did little more than copy Miiller's 

 description. Johnston (14) merely mentions the genus to 

 throw doubt on its right to a position in the British fauna 

 at all. 



In 1855, for the first time since Miiller noticed the genus 

 under consideration, we meet with an attempt to give something 

 like an exact account of a new species. In that year a paper 

 appeared from the pen of D'Udekem (6), which must be regarded 

 as the starting-point of all modern work on the subject. Up to 

 that time Dero digitata and D.furcata (the latter of which had 

 almost been lost sight of) had held the field alone ; but D'Udekem's 

 contribution contained a description of a new species, Dero 

 ohtusa, clearly expressed, and accompanied by a figure which 

 rendered it easily recognizable. 



In 1872 Perrier (22) published a very interesting and exhaustive 

 account of a species which he identified with that described by 

 D'Udekem ; and the fact that he was wrong on this point in no 

 way detracts from the value of his observations, whilst his figures 

 are almost all tliat could be desired. In acknowledgment of 

 Perrier's work, I have named the species which he studied Dero 

 Perrieri, it being new. 



Prof. Leidy (15), in a paper of which he has kindly sent me 

 a reprint, describes two worms, one of which he calls Dero limosa 

 and the other Aulophorus vagus. The former appears to be 

 identical with a species found abundantly round London ; the 

 latter is considered by Prof Leidy to be identical with that 

 described by Eosel {loc. cit.), the Dero furcata of Oken ; and 

 apparently Prof Leidy 's distinction is based upon the fact that 

 he found the latter free. 



Semper (20) has described two species under new names, his 

 Dero pJiilippinensis being apparently the same as Dero limosa just 

 referred to, whilst Dero Bodriguezii is undoubtedly the same as 

 the Aulophorus vagus of Leidy, Dero furcata of Oken, and Dero 

 pal'pigera of Grebincky. 



Tauber's work (29) contributes nothing to our knowledge of 

 the genus, being merely a catalogue of Danish Annulata. He 

 remarked that the genus is rare in Denmark. 



The magnificent work of the Bohemian Professor Yejdovsky 

 (31) contains a full list of names and synonyms of tlie species of 

 Dero known up to the date of his publication. Unfortunately 

 he observed only a very few examples of the genus, the species 



8* 



