BT T. HARVEY JOHNSTON AND O. W. TIEGS. 113 



modified in such a way as to present numerous concentric rows consisting each 

 of a pair of laterally elongated lamellae. Eyes present. Intestine ends blindly. 

 Cirrus simple. ' Vagina present. From the gills of marine fishes. 

 Type and only species, L. typicus J. and T. 



Lamellodiscus typicus, n.sp. (Plate sxi., figs. 74, 78, 78a.) 



A rather small worm, measuring about .124 mm. in greatest width and .528 

 mm. in length. The anterior end is narrow, especially immediately behind the 

 phai'ynx, while in the region of the testis the worm is at its maximum breadth, 

 there being a distinct constriction immediately before this region. Disc con- 

 nected with body by a rather long pedicle. 



The disc bears four large hooks of which the ventral is somewhat bifurcated 

 at its base (PI. xxi., fig. 74). All four articulate with a strong chitinous cross- 

 bar. Seven minor hooks are present, their dispositions being as indicated in 

 PI. xxi., fig. 74. The accessory disc (sqnamodisc) undergoes a remarkable deve- 

 lopment, each of the concentric rows consisting, not of scaly papUlae as in the 

 other Lepidotreminae hitherto described, but of a single pair of laterally-elongated 

 lamellae. 



The integument is remarkable in that no trace of scaly papillae could be 

 discovered. This is perhaps correlated in some way with the curious develop- 

 ment of the squamodisc, a structure which, as already stated, is probably pro- 

 duced as a modification of these scaly papillae. The muscle-system is feebly 

 developed, the transverse system being scarcely evident in preparations. In the 

 posterior region, however there are two pairs (a dorsal and a ventral) of 

 bundles of longitudinally running fibres passing to the disc (PL xxi., fig. 74). 



The cephalic glands are well developed and lodged on each side of the 

 pharynx in a pair of distinct swellings (PL xxi., flg. 78), their ducts travelling 

 foi-ward to open through three pairs of head-organs. 



The mouth is situated sub-terminally; the pharynx is very small, and the 

 oesophagus extremely short. The intestinal limbs are entirely devoid of caeca 

 and end blindly a little before the disc. 



Two pairs of eyes are present immediately in front of the pharynx; those 

 of the posterior pair being larger and closer together than the anterior. The 

 brain is situated beneath them, but no details of the nervous system could be 

 observed. 



The testis is situated in the middle of the body and is so large that it pro- 

 duces a distinct bulging of the body in this region. The vas deferens appears 

 to originate at its posterior portion; it travels foi-ward, then turns inward 

 towards the midline and then forward again to pass as a rather widely dilated 

 duct serving as a seminal vesicle, into the region of the cirrus, narrowing 

 suddenly before it enters the latter structure from above. The cirrus is a 

 medium-sized, simple chitinous tube, passing directly backward to terminate at 

 the male genital aperture. 



The ovary is a curved organ lying just in front of the testis. The oviduct 

 passes inward from its most anterior portion and then forward as the uterus. 

 The vagina is a simple thin-walled tube, which appears to be lined with a thin 

 layer of chitin. It passes backward, crosses the path of the uterus, then turns 

 inward and forward again and opens into the ootjrpe. There is formed a small 

 distension in its posterior region, which apparently serves as a receptaculum 

 senunis. Shell-glands could not be seen. 



Tlie vitelline system is very well developed. It closely follows the limbs 



