284 ORDER SYNODONTIA 



one-fourth as great as at the anus. Posterior two-fifths of the tail armed with 

 short, backward-pointing, arcuate, acute thorn-like setae to the number of ten 

 on each ventrally submedian line. No caudal glands. The lateral fields appear 

 to be fully one-third as wide as the body. The excretory pore appears to be con- 

 nected with a large, ellipsoidal ampulla, nearly half as wide as the neck. The 

 position of the renette cell has not been determined. From the depressed vulva 

 the vagina leads slightly forward. Beyond this fact little is known concerning 

 the internal organs. As no traces of ova have been seen behind the vulva it is 

 assumed that the organs are asymmetrical. 



Habitat: Mud, tide pool, low tide, Portsmouth, N. H., U. S. A. The single 

 specimen examined contained numerous yellowish, spherical/^crystalline bodies, 

 arranged in an obscurely double series, beginning at the base of the neck and 

 ending at the anus. Whether these are natural or have been induced by the 

 method of preservation remains to be determined. The peculiarities of the spe- 

 cies justifying the establishment of a new genus are as follows : (1) the formation 

 of the pharynx and of the lips with their distinct forward-pointing appendages; 

 (2) the unusual size and form of the amphids; (3) the absence of caudal glands; 

 and (4) the peculiar thorn-like setae on the tail. These, combined with the very 

 slender form, make it difficult to refer this specimen to any known genus. Fig. 

 68, p. 283. 



69a. Monhystrium transitans n. sp. Type species. Cuticle naked, except for 

 the setae on the head. Lips three, more or less confluent, thick and mobile. 

 Pharynx double; the closed lips forming a narrow vestibule reaching one-third 

 the way to the base of the pharynx. Anterior chamber of the pharynx pyramidal, 

 the posterior more of less napiform. The lips come to a sharp edge, and are 

 stiffened by several refractive "plates," whose direction is radial but indefinite, 

 as if due to the folding of a cutinized membrane. Oesophagus cylindroid, end- 

 ing posteriorly in a pyriform cardiac bulb five-sixths as wide as the base of the 

 neck. Its lining finds expression in three longitudinal lines, occupying a space 

 equal to two-sevenths the width of the whole organ. Its musculature is rather 

 coarse. There is no cardia. The thick-walled intestine, which has a distinct, 

 refractive lumen, is set off from the oesophagus by a constriction one-fourth as 

 wide as the base of the neck, and becomes at once three-fourths as wide as the 

 body. Its cross-section shows two cells. In contour, it is more or less crenate, 

 at least in alcoholic specimens, because of the pronounced nature of the intestinal 

 cells. These latter contain numerous granules of rather uniform size. The 

 walls of the intestinal cells are refractive. The tail is at first conoid, then cylin- 

 droid in the posterior two-fifths. It tapers from in front of the anus to the almost 

 imperceptibly swollen, more or less apiculate, unarmed, symmetrical terminus, 

 which presents a profile similar to that of a swan's head. It bears a simple, 

 unarmed, blunt spinneret. Only two caudal glands are to be seen; these are 

 broadly saccate cells, forming a close tandem in the anterior third of the tail. 

 The more or less finely granular longitudinal fields are one-third as wide as the 

 body. The post-cervical renette cell empties through the excretory pore a little 

 in front of the nerve-ring by means of a more or less spherical ampulla, and final 

 slender duct one-half as long as the body is wide, leading therefrom to the 

 excretory pore. The vulva is large and more or less elevated. The ellipsoidal 

 eggs are three-fourths as long as the body is wide and are deposited after seg- 

 mentation; it is probable that the species is viviparous, or ovoviviparous. The 

 small posterior branch of the sexual organ is one-half as long as the body is wide. 



