KUKGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 63. N:0 2- 11 



irregular, wart-like prominences. Form of body irregular, generally sub- 

 conical, somewhat compressed from side to side. 



P. pomaria Savigny 1816. 



Dendrodoa Mac Leay 1824. 



I. Testis not separated from the ovary, both forming one hermaphroditic 

 gonad, testis being placed on the outer side, ovary on the inner side of 

 the gonad. Vasa efferentia open by many very short ducts, placed on 

 the inner free side of the gonad. Opening of the dorsal tubercle horse-shoe- 

 shaped. Test minutely wrinkled or strongly tuberculate. 



A. Gonad unbranched, cylindrical, straight. 



Branchial sac usually with only one vvell developed fold on the right 

 side. D. grossularia Van Beneden 1846. Pl. 2, figs. 34 — 38. 



B. Gonad divided into branches. 



1. Branchial sac with intermediate longitudinal vessels. The four 

 branchial folds are well developed or the second is rudimentary. 

 Gonad typically five-branched or with from two to many branches. 

 Test minutely or coarsely wrinkled, sometimes tuberculate. 



D. aggregatet, Rathke 1806. 



a. Branchial folds well developed. 



Gonad five-branched. Stomach elongated, bent to form almost 



a right angle, not distinctly marked off from the intestine, with 



longitudinal folds externally conspicuous. Intermediate vessels 



usually two to three. forma typica. 



Pl. 2, figs. 39—40. Pl. 3, figs. 43—44. 



Gonad three-branched. Stomach elongated vertically placed, straight, with longitu- 

 dinal folds. Intermediate vessels about two in number. 



var. adolphi Kupffer 1874. 



Gonad tbur-branched. Stomach short, horizontally placed, distinctly marked off from 

 the intestine, with longitudinal folds. Only one intermediate vessel between the folds 

 in the branchial sac. var. cylindrica Bjerkan 1911. 



Gonad usually three-branched. Stomach elongated, curved, with 



externally smooth wall, not distinctly marked off from the 



intestine. Intermediate vessels about two or three. 



var. groenlandica n. var. Pl. 2, fig. 42. Pl. 3, figs. 45 — 46. 



Gonad with more than tive branches. Stomach elongated, not distinctly marked off 

 from the intestine, externally smooth-walled, curved. Intermediate vessels of varying 

 number. Test characteristically tuberculate. var. tuberculata Ritter 1899. 



b. Branchial folds more or less reduced. 



The second fold on each side is rudimentary. One to two in- 

 termediate vessels. Gonad two- or three-branched. Stomach 

 short, distinctly marked off from the intestine, longitudinally 

 folded. var. pulchella Verrill 1871. 



(syn. D. kilkenthali Hartmeyer 1899). Pl. 2, fig. 41. 



