554 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxi. 



ment of which the vascular sacs of the vesicles are formed. The ante- 

 rior region of the mature as well as of the young specimen is depressed, 

 as .in T. macidata, instead of terete, but the annulation, although 

 obscured by cutaneous folds, appears to be the same. Exclusive of the 

 three obscure annulations observable on the dorsum of the head there 

 are twenty prevesicular annuli, of which the last is united with and 

 retracted into the border oi' somite XII. 



Three complete anteclitellar somites are recognizable, owing to the 

 presence on their first and second primary rings (namely, six and seven, 

 nine and ten, and thirteen and fourteen) of peculiar cutaneous pro- 

 jections just dorsal to their lateral margins. These are usually, but not 

 invariably, united into a single pair on each somite, and are probably 

 of the nature of rudimentary resi)iratory vesicles, or at least lioino- 

 dynamous structures. They lie somewhat dorsal to the plane of the 

 functional vesicles. 



The clitellum consists of two relatively large annuli, which are united 

 together and bear a pair of cutaneous appendages in strictly marginal 

 position, and four narrow biannulate annuli, of which the first contains 

 the male and the third the female orifice, thus agreeing with T. macu- 

 lata. The last, and frequently the female ring also, is contracted within 

 the following somite. 



In the posterior region the integument, which must have been very 

 loose in life, is much wrinkled and thrown into folds in contraction. 

 This condition is less marked in the young example, in which the three 

 primary annuli are readily recognized, and the first and second are 

 seen to be occupied by the remarkably large respiratory vesicles. Each 

 of the primary annuli, of the adults is marked by four more or less dis- 

 tinctly marked transverse folds, which are divided by longitudinal fur- 

 rows, into quadrangular tile-like and slightly raised areas, giving to 

 the entire surface«a rugous tessellated appearance. 



The respiratory vesicles are very large and conspicuous. They occupy 

 the margins of the first and second primary annuli of each somite, and 

 are connected by a cutaneous fold which is continuous along the mar- 

 gins of the body from the first to the twelfth or last pair of functional 

 vesicles. Delicate irregular cutaneous wrinkles roughen the surface 

 of both the vesicles and the marginal fold. 



The posterior sucker is small, straight, and shallow; the anterior is 

 closed in contraction to a vertical slit. No pigment remains in the 

 bodies of any of the specimens, which have faded to a uniform clay 

 color. A few brown pigment cells are arranged in a zone across the 

 head anterior to the annulations. There are no eyes. 



The specimen figured has the following measurements : 



mm. 



Length complete 23 



Leugth of anterior region 3. 3 



Width of clitellar region 1. 3 



Width at first pair of vesicles 2. 4 



Width at ninth pair of vesicles 5. 8 



Types. — No. 5035, U.S.X.M. From red snapper. Six specimens. 



