414 UESClill'TION OF THE PLATES. 



Fig. 2. 5n(7««aiV«j-ianrt greatly magnified; natural size quarter of an inch. 

 I believe this to be a new species, and I have named it the Mari- 

 ana. The ova are seen on each side of the alimentaiy canal ; 

 and in the lower half of the body are the cells containing sper- 

 matozoa, which issue from the orifices in the fin near the tail. 



... 3. Nymphon f/ractlc (one of the Pycnogonida) ; natural size. The 

 three circles from which the legs spring convey an inaccurate 

 idea of the reality ; they are not cavities, but enlargements of 

 the trunk. 



... 4. The same animal in the egg, just before it is hatched; greatly 

 magnified. 



PLATE VI. 



Fig. 1. Synr/nathus anguineus (Pipe-fish), about half the natural size. 

 2. A Comatula rosacea. (Copied from Forbes.) 

 ... 3-10. Development of Stron{/i/liis auricniaris, one of the Entozoa. 

 Fig. 3 shows the primary germ-cell, surrounded by the 

 yolk ; at 4, a division has taken place ; 5, a subdivision ; 6, 

 stiU further subdivision; 7, the repeated subdivisions have 

 resulted in what Is called the "mulberry ma.ss," out of 

 which the embiyo is gradually envoled as in figs. 8, 9, 10. 

 (Copied from Bagge.) 



PLATE VIL 



Fig 1. Terehella nehulosa removed from its tube. The tentacles are 

 both longer and more numerous than here represented ; and 

 the gill-tiifts at the side of the head are more apparent. 

 (Copied from Rymer Jones.) 



... 2. An ideal represent;vtion of the brain and spinal chord, sho\ving 

 how the nerve-fibres are theoretically supposed to communicate 

 with the nerve-cells of the grey matter of the chord, and thence 

 pa.<*s up to the brain, terminating in the cells of the grey matter 

 of the convolutions. (Copied from Leydig.) 



... '.i. A. Plenrobranchns, natural size, seen from above. 



... 4. A. stem of the Cnrl-xrrew Coralline, natural size. 



PRINTKD BY WILLIAM BLACKWOOD AXD SONS, EDLNBrKOH. 



