ZooL.— Vol. II.] EISEN—OLIGOCHMTA. 89 



4. Set£e c and d in somite II are not in line with set^ 

 c and d in somites III, IV and following; but setee c in 

 somite II are in line with setae d in III and IV, and setae d 

 in II are more dorsal than setae d in the other somites. 



5. Setae c and d in somite II are somewhat larger than 

 any other of the anterior setae. 



6. The spermathecae are much longer than those figured 

 by Perrier. The duct is about four and a half to five times 

 the length of the pouch and about one-third its width, 



7. There are no extra blood capillaries in the caudal 

 zone, such as those described by Horst in his account of 

 Pontoscolex corethrurus. 



8. The male pore is on the anterior part of somite XXI 

 and not in the intersegmental groove. Whether this is a 

 constant feature I am unable to say. The pores are not 

 visible from the exterior. 



9. There is a large prostomium which is generally 

 found retracted in preserved specimens. 



10. The caudal zone is characterized by a large number 

 of what seem to be sense-cells without terminal sense-hairs. 



11. In the anterior part of the anterior somites the 

 longitudinal muscular layer is separated from the trans- 

 verse muscular layer by vacuoles traversed only by isolated 

 strands of mixed muscular tissue. 



Affinity. — After a consideration of the foregoing pecu- 

 liarities in structure, the question naturally arises whether 

 the form of Pontoscolex from Tepic and Baja California is a 

 variety, a subspecies, a distinct species, or, perchance, 

 identical with the Pontoscolex corethrurus described b}'^ a 

 number of investigators. With our present knowledge of 

 the anatomy of the type-specimens of P. corethrtirus and 

 of those specimens from other localities which have been 

 referred to this species, this question cannot be satisfactorily 

 answered without a re-examination of all the types. The 

 descriptions given by the various investigators either differ 

 considerably from each other in essential points, or they are 

 insufficient to enable one to satisfactorily determine a speci- 

 men. Dr. Rosa (i) has, as is well known, endeavored to 



