j 72 < s - 



THE MONONCHS 



44. M. gracilicaudatus n. sp. Intestine about 12 cells in girth. The anterior 

 fifth of the tail is arcuate conoid in such fashion that at the beginning of the second 

 fifth the diameter is about one-third to one- 1.4 4.8 z\. -M^ 8 65. 

 fourth as great as at the anus. Thence on- FTs fTi fTa TTs i.e' D-l B 

 ward the tail tapers very gradually through the middle third, the posterior portion 

 being cylindroid and somewhat narrower than the spicula. These latter are uni- 

 formly arcuate, and about one and one-fourth times as long as the anal body- 

 diameter. At their widest part, toward the proximal end, they are about one- 

 fifth as wide as the corresponding part of the body. They taper gently in each 

 direction, and are not cephalated. The small accessory pieces are of typical form, 

 only about one-fourth as long as the spicula. The series of 19 contiguous supple- 

 mentary organs is twice as long as the spicula, or equals 3 body diameters. Anteri- 

 orly the organs are somewhat larger and also somewhat farther apart. The conical 

 exterior portion of each organ seems to be more or less protrudable. These organs 



X750 



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are similar in form to those of major, though they are not echinulate. The anal 

 and post-anal muscles are strongly developed. The anal muscles are found through- 

 out the bulkier portion of the tail. The protruding muscles of the spicula extend 

 backward in the tail to near the point where the tail diminishes rapidly in diameter, 

 and there join the ventral part of the caudal wall. The post-anal papillae are con- 

 fined largely to the more massive anterior fifth of the tail. On each side there is 

 a ventrally submedian row about as long as the spicula, consisting of 4 to 5 mem- 

 bers. Coextensive with them is a ventral row of 3 to 4 papillae. A little distance 

 behind these, Avhere the tail begins to be smaller, there are 2 dorsally submedian 



