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 fibres, between which occurred 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 Reduced from drawing x \. i.y. —inter-nasal groove. c.p.= 

 chin pit. y.s. =yolk-sac. 

 ,. 2. Skin of embryo 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. ce.s. = oesophagus. 

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

 i.s. =spiral intestine (slit open), rect. =rectum. r.g. =rectal gland. 

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

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

 v. = ventricle, a. = auricle. 

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

 x 20. i.f. = internal folds, mas. = muscle fibre strata. nuc. =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 an afferent branchial. 



