388 PROCEEDINGS OF THE ACADEMY OF [May, 



Tubifex benedeni Udekem. 



Tubifex benedii Udekem, 1855. 

 Clitellio ater Claparede, 1862. 

 ClitelUo irrorata Verrill (in part), 1873. 

 Hemitubifex benedii Beddard, 1889. 

 Psammoryctes benedeni Michaelsen, 1900. 



In its usual form this interesting species is at once distinguished 

 from any others of our marine ohgochsetes by the nearly black or deep 

 gray color, resulting from the remarkable flattened papillae filled with 

 greenish-gray granules with which the cuticle is thickly studded. 

 These papillse are arranged in irregular transverse rows in all regions 

 except the prostomium, peristomium and clitellum, but they differ 

 greatly in size and consequently in conspicuousness in different regions, 

 being largest on the segments following the clitellum, and thence gradu- 

 ally decreasing in size toward the posterior end, where they are small 

 and widely separated. There is also much individual variation in 

 respect to the number and size of these papilli3e, and it seems probable 

 that they may be shed and developed periodically, though my oppor- 

 tunities for observing this species over a period of time have been veiy 

 limited. Certain it is that small individuals with nearly or quite 

 smooth cuticle are frequently found living with fully papillated mature 

 ones, from which they appear to be otherwise indistinguishable. Fully 

 grown worms with the papillse scarcely developed also occur, and some 

 of these are among the material collected by Prof. VerriU at Savin 

 Rock, near New Haven, Connecticut, which is one of the type localities 

 for Clitellio irrorata. It is quite evident, from a careful study of Prof. 

 Verrill's description, that his account of the setae is derived largely from 

 specimens of this species in which, as is frequently the case, some of these 

 organs were broken or abraded, and the others exhibited the normally 

 great variability in the length of the distal process. When as slightly 

 developed as in the specimens mentioned, the papillae might be readily 

 overlooked as unimportant. In my experience the capillary setae are 

 more often absent than present. That the European worm also is 

 variable in these respects is shown by discrepancies in the several 

 descriptions, and by the numerous names that have been applied to 

 the species and listed by IMichaelsen. So far as studied the internal 

 anatomy of American examples agrees f ulty with the accounts given 

 by Claparede, Beddard, etc. The spermatophores are very large, but 

 less slender than in Clitellio arenarius. 



This black worm is widely distributed on the seashores of Europe 

 down to a depth of 7 fathoms. On our coasts it has not hitherto been 

 identified. It is common between tides on muddy shores strewn with 



