KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 59. NIO 3. 59 



The nervöns system has taken part in the general distortion of the body 

 inasmuch as the left cerebral ganglion lies higher than the right one. Buccal 

 ganglia are present. The cerebro-visceral connectives run only in their front part 

 and for a short distance through the liver, mostly outside it, on the right side close 

 beneath the body surface and on the left side midway between the stomach and 

 body surface. The left cerebro-visceral connective describes a wider curve upwards 

 than does the right one. 



The gills. On the left side these are extended into the umbonal protraction. 

 As usual the gills are folded, each fold containing between 30 and 40 filaments. 

 The folds are peculiar in having their opposite walls intimately united intraplicatur- 

 ally, so that they appear as extremely thin laminae. Beneath the point where 

 vena branchialis enters into the axis of the gill there are also established inter- 

 marginal connections with the free margin of the reflected laminae, exactly as in 

 Echinochama arcinella. Otherwise the same conditions seem to prevail as in that 

 species, but details could not be established because of the bad state of preservation. 



The descending lamina of the posterior gill is much reduced in size. 



The kidneys. The elevation of the left umbonal region has influenced the 

 situation and the correlation in size of the nephridia. The left one is wider and 

 extends farther above and below than does the right nephridium, inasmuch as the 

 former has its upper end in the level of the rectum, while the latter terminates 

 lower. The left expansion has also caused an obliquity in their shape; this is to 

 be observed in transversal sections, from which it appears that both pericardial 

 tubes emerge in an oblique direction from the left and the oscular tubes lie in the 

 same line as the ampullae. The former are very short, the latter lengthened and 

 wholly separated from each other, being embedded in the outer sacs, which com- 

 municate narrowly with each other above the pericardial tubes. These then run at 

 the hinder side of the outer sacs and become narrower, continuing upward till they 

 debouch into the upper ends of the sacs, somewhat earlier in the right nephridium. 

 The lobation of the tubes and the sacs is the usual one for Chamidae, and the ne- 

 phroprocts are situated just below the nephrostomes opposite to and lower than 

 the genital pores. 



No pedal retractors penetrating the nephridia were visible. 



Chama lazarus Linné. 



Figs. 72-74. 



Two specimens from the north-western coast of Australia, collected by Dr. 

 Mj öbérg, were examined in toto and then sectioned for examination of the inner 

 anatomy. 



