SOME PUGET SOUND ASCIDIANS. 603 



Dorsal Lamina : A broad membrane with its free margin ir- 

 regularly cut and toothed ; passing part way round the opening 

 of the oesophagus which is placed nearly at the lower extremity 

 of the branchial sac (PI. XX., Fig. 27). 



Dorsal Tubercle : Raised above the level of the branchial 

 sac. Mouth of the hypophysis crescent-shaped with the horns 

 coiled in, forming small spirals ; opening toward the left side. 



Digestive Tract : Forming a narrow loop ; stomach long 

 and narrow, marked with numerous longitudinal lines which are 

 formed by the folds within the stomach. 



Heart : Very conspicuous, a long slender tube lying close 

 against the lower side of the stomach, but closely attached to 

 the mantle by large vessels. 



Gonads : Numerous, eight to ten on each side of the body, 

 in the form of long, slender tubes, sometimes bent on themselves 

 and somewhat twisted : each tube ending in a large but short 

 vas deferens. Endocarps numerous (PI. XX., Fig. 28.) 



There are six specimens of this species in the collection. Of 

 the six, three have their long axis directed anterio-posteriorly, 

 while the other three have it in the opposite direction. These 

 latter three, however, show signs of being much contracted. 



This species agrees in many particulars with S.joaucE Herd- 

 man '98, but differs from it in external form and color, S.joance 

 being " whitish gray." (Since Herdman himself collected the 

 single specimen upon which his description is based reference 

 is of course here made to the color in life.) The muscula- 

 ture of S.j'oancE is said to be "very delicate," and the mantle 

 thin. The dorsal lamina is a "plain narrow membrane," and 

 the tentacles are "long and slender, closely placed, about forty 

 in number," apparently not differing greatly in length, as is the 

 case in S. stinipsoiii. It is also closely related to Polycarpa 

 fiwnarkiensis, Kiaer '93, but from this it differs in having a much 

 larger number of tentacles, twenty to twenty-five being the 

 number in this latter species ; in the uncoiled condition of the 

 horns of the hypophysis mouth of P. fininarkiensis, and in the 

 absence of toothing (presumably so, since no mention is made of 

 the teeth by the author) on the edge of the dorsal lamina of the 

 European species. 



