PLANARIANS FROM MAURITIUS AND RODRIGUES 135 
and two pairs of laterals. The median stripe is very fine, 
extending from the neck to the posterior extremity, and widen- 
ing slightly above the pharyngeal region. The inner pair are 
much the strongest of all, and the outer pair at the edge of the 
body become indistinct as they approach the hind end; on 
either side both coalesce at the neck into a black patch. The 
head is marked with a crescentic black pattern. Ventrally, the 
worm is similar in coloration to the dorsal surface, with a 
darker shade at the outer edge and also next to the surface of 
the sole ; this latter is very pale. 
TEXT-FIG. 2. 
Eyes of Placocephalus isabellinus Geba. 
The numerous eye-spots are distributed all round the head, 
and are continued sparsely. for a considerable distance along the 
sides of the body. At the sides of the neck they extend some- 
what to the ventral surface and form a patch, as seen in Text- 
fig. 2. 
The mouth-opening, which leads into the peripharyngeal 
chamber, is placed at some distance in front of the centre of the 
body. In the specimens examined the pharynx was protruded 
through the mouth-opening as a creamy frill. 
The genital organs were unfortunately yet undeveloped in 
the individuals examined. Like some other forms, this species 
may to some extent reproduce asexually by transverse fission, 
as stated by von Graff. On two occasions the severed hind end 
presented a concave edge, apparently forming the new tail-end. 
