134 CALIFORNIA ACADEMY OF SCIENCES. 



Spei-mduds are considerably thickened, but the lower part is not any thicker 

 than the npper part, as in B. nana. 



Qonadx are affixed high up on the septum and not at the junction with septum 

 and body-wall. 



Prostates. These bodies are larger than in B. nana, but nevertheless generally 

 confined to one somite each. The penial setae are, as usual, of unequal size. The 

 larger seta is furnished with four notches, the smaller is spoon-like and forked at the 

 apex. 



Nephridia. These organs are arranged in three distinct rows on either side of 

 the median line, but the nephridia in each somite are of unequal size. The nephri- 

 diura nearest the ventral ganglion or nephridium a consists of two, more or less, 

 separate parts, evidently a tendency to diffusion or an imperfect centralization. The 

 most ventral part is the smallest and the most distal the largest. The ducts run con- 

 tinuously between these parts, but the ccelomic cells are grouped in such a way that 

 the bridges between the two parts are quite narrow. The'nephrostome of nephridium 

 a was always plain and readily seen, but I never succeeded in finding the nephro- 

 storaes of band c. Still, these nephridia appear perfectly formed on the meganephric 

 principle, and I could never see any connection by canals between a and b, and b and 

 c, though sometimes the coelomic cell masses extended more or less continuously over 

 and between the respective nephridia a, b and c. 



Nephridia a open in front of setse 1 and 2, while in B. nana they open in front 

 of 3 and 4. The most anterior nephridium possessing a ccelomic covering I found in 

 xxi. Through the courtesy of Dr. Michaelsen,' I have received specimens of B. 

 Bolavi for comparison. The nephridium of B. palmicola resemble that of B. Bolavi, 

 but is much larger, and the respective nephridia cover each other slightly, while in 

 the two specimens of B. Bolavi which I dissected the respective nephridia were sep- 

 arated by considerable distance; the latter nephridia are also smaller. I had at first 

 intended to assign these species of Benhamia possessing several nephridia of a perfect 

 form under a separate subgenus, when my attention was called to the fact, by Dr. 

 Michaelsen, that B. Stuhhnanni sometimes possessed a similar arrangement of nephri- 

 dia as those in B. Bolavi, etc. As the nephridia of B. Stuhlmanai are generally 

 plectonephric or diffuse, it became at once evident that this distinction could not be 

 used as a generic character of value, and that it really is impossible to draw any dis- 

 tinct line between a plectonephric and a micronephric condition. It is, however, en- 

 tirely incorrect to characterize these nephridia as a mass of tubules, etc., as wherever 

 they are separated one from the other, as in Bolavi, palmicola, nana, rugosa and 

 probably great many other species, each micronephridium is perfect in itself, and built 

 on the same general principle as the meganephridia of the other terricolne. I would 

 therefore propose to make a distinction between plectonephidia, or really diffuse 

 nephridia, and micronephridia, or nephridia of small size, but perfect, or built on the 

 meganephric plan. Such a distinction maybe useful in descriptions, even if they are 

 not morphologically distinct. 



