MYZOSTOMIDA FROM THE RED SEA. 101 



possessing a single nephi^ostome as well as an unpaired end -piece 

 opening into the rectum ; a similar condition is to be found in 

 M. crypiopodium, where, however, the median end-piece opens 

 directly to the exterior on a papilla just under the cloacal orifice. 

 Moreover, according to Wheeler, in M, belli the cloaca, oviduct, 

 and nephridial end-piece open separately on the posterior surface 

 by three ciliated apertures. 



Beard's suggestion as to the nature of the oviduct was forgotten 

 when the nephridia were discovered, and, whilst not wishing to 

 commit myself to this theory, I recall it as one to be borne in 

 mind. Perhaps Protomyzostomum 2Jolynej3hris wiW afford clues to 

 a number of such problems in the morphology of this difficult 

 group of animals. 



Myzostoma eubrofasciatum v. Graff. (PI. VI. fig. 1.) 



If. rahrofasciatum v. Graff (8), p. 33, pi. ii. 



In Mr, Crossland's collection are two specimens of a Myzostoma 

 from Forculch Barrier Island, obtained from a Comatulid which 

 unfortunately cannot now be traced. 



The animals are of an oval shape, but, owing to the contraction 

 of the bodies being accompanied by a curling-up of the anterior 

 and posterior ends (c/, PI. VI. fig, 1), it is impossible to give exact 

 measurements. One specimen is a little larger than the other, and 

 must have had a length of about 2| mm., with a maximum 

 breadth of 2 mm. ; the smaller specimen measures approximately 



mm. by 1-75 mm. 



The body is of considerable thickness ; on the dorsal side is a 

 very conspicuous median longitudinal elevation running from one 

 extremity to the other ; narrow at each end, it is very broad 

 towards the centre of the body, where it reaches a bi-eadth almost 

 one-fifth of that of tlie whole animal. From the sides of the 

 median elevation arise seven to eight broad radial ones extending 

 to the body-margin, where they end in short blunt processes. 

 Between these primary radial " costee " are a number of shorter 

 secondary and tertiary ones, these are also of considerable 

 breadth, and terminate in marginal processes. 



The costae are so numerous near the edges of the body as to 

 come in contact w^ith one another laterally, thus forming a thick 

 ribbed margin, a very conspicuous feature of this species. As 

 mentioned above, the body-margin presents a series of short blunt 

 processes formed by the terminations of the radial elevations; 

 there are between 25 and 30 pairs of these processes, which are 

 very irregular in size and shape. In both specimens, however, 

 the last pair and, to a slightly less degree, the penultimate and 

 antepenultimate pairs, are considerably enlarged and thickened. 



The coloration of the dorsal surface in the preserved specimens 

 is peculiar and very characteristic ; the median elevation and the 

 costfe are of a yellowish colour ; the rest of the dorsal surface is 

 brownish, except where a pair of narrow light-coloured streaks 



