204 Messrs. T. and A. Scott on some new or rare 



between the head and first thoracic somite, which in some 

 positions has the appearance of a true joint, especially if the 

 specimen has been a considerable time in spirit ; the forehead 

 is rounded and furnished with a very small rostrum. The 

 last body-segment is produced laterally near the distal end 

 and on the dorsal aspect into two digitiform processes, as 

 shown in PL XVI. figs. 2 and 3. Anterior antennae very 

 short, stout, three-jointed, truncate at the end, and armed 

 with several terminal, somewhat conical teeth, the two upper 

 being considerably larger than the others ; the first joint is 

 proportionally large, the second and third very short (fig. 4). 

 Posterior antennae two-jointed ; the end of the last joint 

 bears four conical teeth, one terminal and three marginal 

 (fig. 5). ? Mandibles rudimentary, composed of three nearly 

 equal and rounded lobes (fig. 6). Anterior foot-jaw small, 

 one-jointed, and bearing two terminal spines (fig. 7). Pos- 

 terior foot-jaw large, three-jointed, considerably dilated at 

 the base, but gradually decreasing in breadth towards the 

 extremity and armed with a short but stout terminal claw, 

 which has a broadly rounded lobe on the inner edge (fig. 8). 

 The first four pairs of feet are nearly alike, and resemble the 

 posterior antennas in general appearance : the inner branch of 

 all the four pairs is a short and broad rudimentary appen- 

 dage apparently unfurnished with spines or setae of any kind ; 

 the outer branch is comparatively narrow and elongate; in 

 the first pair this branch is furnished with four small spini- 

 form teeth, one being terminal and three marginal (fig. 9) ; 

 that of the second pair has one terminal and two marginal, 

 and that of the third and fourth pairs is furnished with one 

 terminal and one marginal tooth (fig. 10). Abdomen very 

 short and rudimentary, composed of three joints, the middle 

 one being smaller than the other two; the end of the last 

 joint is somewhat bifid, and each of the postero-lateral angles 

 terminates in a small tooth-like spine (fig. 11). Ovisacs 

 two, cylindrical, and about twice the length of the animal 

 (fig. 1) ; they are attached at the base and towards the dorsal 

 aspect of the last thoracic segment. Colour opaque white. 



Hah. In the intestine, not the branchial cavity^ of Ascidia 

 '^intestinalis, dredged near Inchkeith, Firth of Forth. 



Remarks. — Four specimens of this parasite were obtained 

 in the intestine of four Ascidians (one in each Ascidian) 

 during March 1891, and are recorded in the ' Ninth Annual 

 Eeport of the Fishery Board for Scotland,' part iii. p. 301 ; 

 one of these possessed a small portion of the basal part of 

 two ovi-sacs. A short time ago another specimen of the same 

 parasite was obtained in the intestine of the same species of 



