105 



Fig. 77. Median vertical longitudinal .section of arm, 

 showing the ganglion and group of nerves, 

 which supply each sucker. 



Fig. 076. Diagrammatic longitudinal section through 

 two ova, showing their mode of attachment to 

 the germinal wall, and also numerous folds of 

 the follicle, which nourishes the developing 

 ovum. In left hand corner is a diagram of 

 an egg in transverse section, showing the 

 infolded follicular membrane. 



Plate X. 



Fig. 78. Diagram of median vertical section of eye. The 

 whole optic ganglion is drawn in order to show 

 the relation of the retinal nerves to the retina 

 and ganglion. The small figure on the left 

 shows the outer segment of the lens, from the 

 surface which rests on the cornea. x 2. 



Fig. 81. Diagram of the parasite Dieyema mulleri, found 

 in the kidney fluid of Eledone cirrosa. Much 

 enlarged. 



Fig. 82. Anterior region of visceral envelope, from inner 

 surface, showing posterior membranous wall 

 of brain case, and various nerves. x |. 



Eye from external surface, showing lid and 

 pseudocorneal membrane, x 1. 



Median dorso-ventral section through eyelid 

 and pseudocorneal membrane. x 1. 



(a) Cranial and orbital cartilages, from dorsal 

 surface, (b) The same, ventral view, x |. 



Vertical section through portion of the retina. 



Dorso-ventral section through olfactory pit, 

 much enlarged, showing the folded sensory 

 wall. 



Fig. 60. .Right olfactory pit ; mantle turned back, x 1. 



C. Tinling & Co.. Ltd., Printers, 53, Victoria Street, Liverpool. 



