of the Fishery Board for Scotland. 79 



cells. In the middle layer there was an upper and a lower stratum com- 

 posed entirely of closely-packed muscle tibres, between which occuixed a more 

 loosely-packed stratum. The latter stratum consisted of nucleated cells 

 among which were found a few muscle fibres ; the uterine blood vessels lay 

 in this stratum. This fact is also opposed to the supposition of a placental 

 connection. 



EXPLANATION OF THE FIGURES IN PLATE IX. 



Fig. 1. Embryo A Reihiced from drawing x |. ^.y.= inter-nasal groove. c.p.= 



chin pit. i/.-s. =yolk-sac. 

 ,. 2. Skin of embiyo B. Reduced from drawing x 475. Showing pigment spots 



and a dermal denticle in the process of development. 

 ,, 3. Digestive tract of embryo C. Reduced from drawing x 1. tes. = oesophagus. 



/. =funnel. l.t. = lohed tissue mass. c.i. =tube leading to intestine. 



1.6-. =spiral intestine (slit open), reci. =rectum. r.^. =rectal gland. 

 ,, 4. Heart and branchial arches of B. Reduced from drawing x 1. Ventral 



aspect. I.-VI.=tirst to sixth afferent branchials.* c. =conus arteriosus. 



V. = ventricle, a. = auricle. 

 ,, 5. Transverse section of viterine (oviducal) wall of adult. Reduced from drawing 



X 20. «._/! =internal folds. »m.s-. =muscle fibre strata. ?;iac. =muscle 



fibres and nucleated cells, lac. = blood lacuna. 



* In the light of the probable function of the sixth arterial arch it is perhaps inadvisable 

 to .speak of it as au afferent branchial. 



