156 CALIFORNIA ACADEMY OF SCIENCES. [Proc. p Ser. 



first counted in an enumeration of the somites. Next to 

 the prostomium, this somite is the most modified. Its cirri 

 are the " peristomial " cirri, and are two, four, or eight in 

 number. When two only are present, as in Heteropale 

 bellis, they are the dorsal. A dorsal and ventral peristomial 

 cirrus is present on each side in the Polynoida?. In Chrys- 

 ofetalum, where two pairs are present on each side, the 

 duplication probably does not indicate the fusion of two 

 peristomial somites, but a sort of chorisis or division of an 

 original single pair. The "buccal" cirri are the much- 

 enlarged ventral cirri of the second somite. The "anal" 

 cirri are always a single pair belonging to the terminal or anal 

 somite, which is invariably postanal in Euphrosynidas, Aph- 

 roditidae and Polynoidae. The " nephridial papillee " of 

 the Polynoidae and Sigalionidae are the little protuberances 

 on the ventral side, one at the base of each parapod for the 

 greater portion of the animal's length. At their distal ends 

 the nephridia open. 



Descriptions and measurements have been based almost 

 entirely upon specimens carefully preserved either in alco- 

 hol or formalin. Only in respect to color have I found any 

 advantage in drawing up descriptions from living speci- 

 mens; and there are positive objections to taking measure- 

 ments from the living worms. While I have constantly en- 

 deavored to preserve specimens in a straight and extended 

 condition, I am bound to say that my efforts have been only 

 partially successful. No matter how gradual or prolonged 

 the narcosis, very few species fail to undergo more or less 

 contraction when placed in the fixing fluid. Since meas- 

 urements taken from straight and moderately contracted 

 specimens give quite as accurate an idea of the true dimen- 

 sions of the species as if obtained from living worms, exhib- 

 iting as they usually^ do every gradation of extension and 

 flexion; and since, furthermore, nearly all Annelid meas- 

 urements extant have been made upon alcoholic material, I 

 have seldom taken the trouble to get the dimensions of liv- 

 ing specimens. 



I gladly avail myself of this opportunity to express my 



