ANNELIDA POLYCHAETA. 



43 



Avenicola Grubii Clprd. (figs. 12—15). — Clapa- 

 rède, loc. cit. p. 36, pi. XIX, fig. 2J5, 27. 



This species seems to be very common in the Gulf of Na- 

 ples, for among thirty ^4reraVo/a-specimens from this locality , 

 which I could examine, twenty-five belonged to A. Grubii 1 ). 

 Grube first met with those worms at the shore of Catania; 

 therefore Claparède , who found them afterward at Naples, 

 named the species in honour of that distinguished investi- 

 gator of Annelids A. Grubii. It is to regret that a sin- 

 gular mistake seems to have crept into Claparède's descrip- 

 tion, for we read there: »segmeutis anticis branchiis 

 destitutis decern" and afterward »dans l'espèce napoli- 

 taine, la première paire de branchies est toujours au 

 dixiè me sétigère" 2 ); however those numbers are quite 

 at variance with the description of Grube, who writes: 

 »ich zalilte 38 paar Borstenbündel , von denen die ersten 

 11 isolirt, die übrigen 27 mit Kiemen zusammenstanden.' 

 The exactness of Grube's statement could be confirmed by 

 me, for I found the first pair of branchiae without any 

 exception situated behind the 12th dorsal bristle-fascicle. 

 The largest specimen has 38 setigerous segments. The first 

 pair of branchiae is not smaller as those of the following 

 segments ; however in the posterior region of the body the 

 branchiae gradually decrease in size, and the posterior 

 segments want them totally , or they are only represented 

 by a small filament with a couple of short branches. The 

 branchiae do not consist of secundary branchial leafs, but 

 are arborescent, branching directly at their base; they 

 show 3 or 4 main stems, which divide dichotomously and 

 terminate in numerous filaments. The dorsal fascicles con- 



1) By the liberality of Prof. Hubrecht the Arenicola-syetivaens of the Utrecht 

 Mu9eum were also placed in my hands for examination. 



2) This erroneous description is repeated in Cams'' Prodromus Faunae medi- 

 terraneae ; it is an example to illustrate the dubious valour of such a catalo- 

 gue drawn up without any critic ; had the author could limit himself to a 

 simple enumeration of the species and the litterature , his work should have 

 been less painful for himself, and as useful for the public. 



Notes from the Ley tien Museum, Vol. XI. 



