214 56 



behind a breadth of O'lO 01 ™, the anterior refolded edge had on either side of the pointed 

 hook 3 ( — 4) denticles, the legs which were not of quite the same length, were less spread 

 than usual log. 14). The lateral plates were of the common form; their body (as far as to 

 the bending into the hook) had a length of 0'16 mm ; the hook showed at the upper edge 

 mostly 11 — 12 denticles, sometimes also 7 — 8, at the lower edge 4 ( — 5) denticles. 



The oesophagus as usual with a widening. On the fore side of the yellowish 

 «psalterium» , of a diameter of l'a 1 ™, the common, transversely situated bag (the second 

 cropi is found. The stomach proper and the intestine seemed to be as usual. — The 

 liver was yellow. 



The gill was as usual, its height was up to 2 mm . The olfactory organ iSpengeli 

 had a breadth of up to l-25 mm . 



No developed sexual elements seemed to be found in the ovary. The somewhat 

 flattened mucous-albuminous gland was whitish; the few seminal vesicles were small and 

 white. — The penis of the common form. 



The larvae of the Marseniae, the Echinospira a. s. o. are found widely spread 

 in plankton, and carried far and wide by the currents, and by far most of the forms of 

 Marsenia described as species , are likely to be only local varieties of the Marsenia per- 

 spicua which seems to be almost cosmopolitan 1 ). 



') Among the Marsenia collected by Plate at the western coast of South America I have pointed out 

 several such varieties. Comp. Die Opisthobranchien der Sammlung Plate. Zool. Jahrb. Supple- 

 ment IV, 3. 1898. pp. 564 -569. 



