a crio-antic size indeed. The radula is of a purely distichous character as is obvious trom fig. 159; 

 the radula-bands operate as a pair of scissors. Only the lateral pharyngeal walls carry the 

 radula-bands; the dorsal wall is beset with long cilia, the ventral wall with shorter ones. The 

 structure of the radula-sac is strange here, it being everywhere else a simple evagination of 

 the ventral pharyngeal wall. Here on the contrary the case is complicated ; the pharj-nx has a 

 laro-e ventral offset, but the radula is not directly formed in this; the distal wall is invaginated 

 and it is only on the outside of the invagination that the radula is formed. The radula-sac is 

 encircled by strong muscles, presenting a peculiar structure ; at several parts they broaden and 

 become transparent, with a great number of fine fibres. Sometimes the fibres are not present 

 and in that case the muscles become wholly transparent: nuclei occur only sporadically (fig. 160). 

 Around the pharyn.x these muscles are likewise met with (fig. 152). 



The intestine has no regular septa, but is provided with irregular folds. A secretion 

 consisting of large brownish-green granules is formed by the wall. Figs. 161 — 163 represent 

 the course and opening out of the rectum. 



The cloaca is a spacious cavity, lined with cubical epithelium. A considerable number ot 

 gills are found; about 20 gill-lamellae with strongly folded wall. In fig. 162 at /is a fold of the 

 cloaca-wall, more proximally continuous with the latter. In fig. 163 the cloaca is slightly cross- 

 shaped; it widens more pro.ximally (fig. 164). 2 Strong muscular bundles connect the ventral 

 cloaca-wall with the thin circular muscular layer under the hypodermis (fig. 165). The cloaca- 

 opening is situated in a superficial furrow (fig. 163); here the cuticle is traversed by a great 

 number of thin, closely ])acked spicula, the shape of which cannot be learned from my sections. 



1 do not give a reconstruction of the generative organs with their efferent canals, as 

 the peculiar structure of the cloaca-ducts would interfere with the clearness of the illustration. 



The cloaca-ducts are coloured yellow in m\- figures; for the sake of clearness the part 

 running proximall)- is of a pale yellow, the part proceeding distallj- of a dark yellow. Both the 

 genital glands, stretching a long wa\- proximally contain mature eggs and spermatozoa. The 

 cloaca-ducts pass out of the pericardium as narrow, strongly winding tubes, the right cloaca-duct 

 being for this reason touched in fig. 166 3 times. INIore pro.ximally they widen considerably 

 and become sac-shaped (fig. 171). They do not carry any appendages; they themselves perform 

 the duty of vesiculae seminales; numerous spermatozoa are contained in them. The wall is built 

 up of cubical ciliated epithelium. In figs. 1 69 and 1 70 the part running proximally merges into 

 the part running distally. The latter behaves likewise; it takes a winding course and is dilated 

 at different points. They unite into the precloacal organ, which is large and extends far proxi- 

 mally (/. 0.). Here ajjpendages are absent too. The structure of the portion of the cloaca-ducts 

 running distally is in no way peculiar: cylindrical ejjithelium alternating with very slender cells; 

 more proximally the glandular cells are finely granular with round nuclei at the base, whereas 

 more distally and in the precloacal organ the glandular cells strongly secrete and are entirely 

 filled with deeply staining large granules. 



2 Small copulation-spicula are present (figs. 165, 166 c. s/>.). They are short (0.2 mm.), 

 but comparatively broad and attached to the ventral muscles of the body-wall b)- tolerably 

 strong muscles. Probably the)- are partly calcareous and consist partly of a cuticular mass; it 



