592 PEOF. w. A. heedman's eevised 



('Dorsal tubercle very small. 

 11 j A. Salvcdoris*, Traast (Med.) 



UlTorsal tubercle large A. ffiacialis, Traust. (Arct.) ,;- "- 



f Transverse vessels alternately large and small. 

 9 ] A. tritonis, Herdm. (N. Atl.) 



[ Transverse vessels all much same size 12 



(Transverse vessels slender, apertures both anterior. 

 A. cylindracea, Herdm. (Austr.) 

 Transverse vessels wide, atrial aperture some way back. 

 A. nodosa, Sluit, (Mai.) 



r Intermediate papillie present. 

 8 ] A. tencra, Herdm. (S. Atl. & Mag.) 



[ JVo intermediate papilla pi'esent 13 



r Body very much elongated, siphons conspicuous. 

 13 i A. curvata, Traust. (W. Ind.) 



[ Body not elongated, siphons inconspicuous 14 



-,.{ Tentacles 20-25 A. despecta, Herdm, (A. Arct.) 



^'^ I Tentacles 35-40 15 



(Dorsal tubercle simple, U-shaped. 

 ^.ca?<^ziat, Herdm. (N.W.Eur.) 

 Dorsal tubercle horseshoe-shaped. 

 A.falcigera,'S-e'rAm. (N. Atl.) 



P- /Plication of the branchial sac very slight 16 



[Plication strongly marked 17 



{Apertures both near centre of upper surface. 

 A. aspcra, Heller. (Med.) 

 Apertures not in centre, but at dorsal edge. 

 A. muricata. Heller. (Med.) 



r Surface covered with short hairs. 

 17-^ A. capillata, ^l\nt. (Mai.) 



[ Surface free from hairs 18 



(" No papillae on internal longitudinal bars, 

 is] A. pattda, O.Y.M.. (N.W.Eur.) 



[ With internal longitudinal bars papillated 19 



,q [Body erect, attached by small area posteriorly 20 



I Body i-ecumbent, attached by greater part of left side 21 



Prebranchial zone with papillae 22 



Prebranchial zone not papillated 23 



r Papillag of prebranchial zone very large. 

 22 i A. melanostoma, Sluit. (Mai.) 



[ Papillte small A. prunum, O. F. M. (N.W. Eur. & Med.) 



go /Tentacles numerous, 60 or more 24 



\ Tentacles not numei'ous, 25 to 35 25 



„./ Test very dark coloured 26 



[Test not of a dark colour 27 



{Intermediate papillte on the internal longitudinal bars. *■ 



A. nigra, Sav. (Atl., Eed S.) 

 No intermediate papillae on the bars. 

 A. atra, Les. (W. Ind.) 



jj» /Body free, not attached 28 r 



"^^ 1 Body attached 29 



* This is the A. oblonga of Traustedt's former paper, 

 t This may possibly be the young of . some other species. 



20 



