DORSIBRAKOHIATA. 377 



(Fig. 510) has recently been described and figured by 

 Professor Verrill.* 



FIG. 510. 



Marine Worm, Cirratultis grandis, Verrill. 



* Cirratulus is grouped with the Dorsibranchiata of Siebohl. But Pro- 

 fessor Verrill writes me that he does not recognize Dorsibranchiata as a nat- 

 ural group, but merely au artificial one. 



" The long, slender organs on the nicies of the body of Cirratulus are the dor- 

 sal cirri, and are not homologous with the branchiae of Arenicola, etc., though 

 they may, and doubtless do act to some extent as branchiae. But they are 

 more particularly devoted to sensation nncl locomotion. Some of the moat 

 anterior ones, however, are different in structure from the rest, though similar 

 in form, and are regarded as true branchiae." Verrill. 



Professor Verrill writes me that he recognizes two Classes of Worms : 



I. ANNELIDA, including six orders, viz. : 1. Chsetopoda, 2. Oligochseta, 3. 

 Gephyrea, 4. Bdellodea, 5. Gymnocopn, 6. Chaetognatha; and II. SCOLECIDA, 

 including six orders, viz.: 1. Nematoidea, 2. Tnrbellaria, 3. Trcmatoda, 4 

 Acanthocephala, 5. Cestocla, 6. Rotifera. 



