NO. 2 hyman: polyclad flatworms FROM THE GALAPAGOS 187 



second glandular region also appears to be subdivided into transverse 

 chambers. It narrows to a wide ejaculatory duct that proceeds straight 

 posteriorly inclosed in a loose muscular region. The ejaculatory duct 

 then narrows and becomes more muscularized ; after a few coils, it enters 

 the proximal end of what may be supposed to represent the penis proper. 

 This is a muscular body with a wavy epithelial lining, which proceeds 

 ventrally and opens by the wide male gonopore. Directly behind this is a 

 deep body indentation that seems to define the posterior wall of the penis 

 as a more penis-like projection. 



The female gonopore occurs some distance posterior to the male pore. 

 It leads into a short tubular female antrum from which the vagina pro- 

 ceeds at right angles, paralleling the ventral body wall. The vagina at 

 first presents several pouches; then, proceeding anteriorly as a straight 

 tube, it makes a backward bend and, paralleling its former course, ter- 

 minates in a bulbous enlargement that receives the two oviducts ap- 

 proaching from in front. The vagina is lined with a cuboidal epithelium 

 and is only slightly muscular. It is surrounded throughout its course, 

 except for the terminal bulb, by the usual cloud of cement glands. 



Differential characters. — The present species is distinguished from 

 all previously described valid species of Cryptocelis by the limitation of 

 the marginal eyes to the anterior body region. In all the others, the 

 marginal band completely encircles the margin. The number of 

 cerebro-frontal eyes is also rather fewer than in other species of 

 the genus, so that in general C. insularis is characterized by a 

 paucity of eyes. The division of the eosinophilous part of the 

 prostatic vesicle into narrow transverse chambers also occurs in 

 C. alba Lang, 1884, and in C. occidentalis Hyman, 1953; and in the 

 latter also the glandular portion of the prostatic vesicle presents two 

 areas of different staining properties. The large glandular diverticulum 

 of the ejaculatory duct described by IAkubova (1909) for C. glandulata 

 has not been found in any other species of the genus ; but a glandular 

 layer surrounding the epithelium of the ejaculatory duct is of common 

 occurrence in the genus, having been reported for all the Japanese species 

 {ijimai Bock, 1923, littoralis Kato, 1937, amakusaensis Kato, 1936, and 

 orientalis Kato, 1939). This glandular layer is also present in C. com- 

 pacta Lang, 1884, from the Mediterranean and in C. occidentalis, Cali- 

 fornia. However, I have been unable to detect it in C. insularis. 



