BY N. A. COBB. 401 



as the length of the spicula, and the second is twice as far from 

 the anus as the first. These are probably accessory sexual organs, 

 and a secretion appears to have flowed from each of them. I could 

 make out nothing concerning the internal structures connected 

 with these swellings, and cannot state positively that they are not 

 slight breaks in the skin caused by the hot sublimate in which the 

 specimen was plunged for fixation. The testicles are situated in 

 the third fourth of the body. 



Hah. — Marine sand, Bay of Naples, 1888. 



VI. MoNHYSTERA, Bastian. 



, ,^ 1- 10- 17- —62-^* 84- 



1. MONHYSTERA DIPLOPS, n.sp. 2^2 3^4 3^5 4^2 3^ 9 mm. I 



have had great interest in examining this beautiful and active 

 little animal. It is so small that all its organs can be examined 

 without difficulty, and yet, notwithstanding its small size, it is 

 one of the most perfectly developed of all the Monhysteras. Its 

 transparent skin seems quite destitute of markings, but bears 

 short inconspicuous hairs throughout the length of the body. 

 The neck is conoid, and terminates anteriorly in a sub-truncate 

 head, whose setae, six in number, are about one-fourth as long as 

 the diameter of the anterior 'part of the neck, though they are 

 somewhat longer on the male. Each of the six lips bears a 

 papilla. The distance of the circular lateral organs from the 

 anterior extremity of the worm is about equal to the width of the 

 head ; the organs themselves are only one-fifth as wide as the 

 head. Two reddish-brown spherical eyes are situated in the dorsal 

 submedian region, just behind the bottom of the pharynx, nearly 

 opposite the lateral organs. The simple conoid pharynx extends 

 to nearly opposite the lateral organs. The anterior three-fourths 

 of the cylindroid oesophagus is only one-half as wide as the neck ; 

 in the remaining part, however, it gradually expands to two- thirds 

 the width of the neck. The lining of the oesophagus, when seen 

 in optical section, is conspicuously crenate. The slightly brownish 

 intestine, separated from the oesophagus by a deep and distinct 

 constriction, is three-fourths as wide as the body. The trans- 

 parency of the cardiac region renders it possible to see the 

 relatively large and deep cardia very plainly. The food seems to 



