26 NILS ODHNER, NORTHERN AND ARCTIC INVERTEBRATES III. OPISTHOBRANCHIA ETC. 



Ancxila Loven 1846. 

 Rhinophores kneed, long, the upper half laminated. Colour white, transparent, 

 ends of the appendages yellow. L. 18 mm. A. cristata (Ålder 1841). 



Pl. in tig.?. 16—17. 



Fam. Aeolididae. 



I. Dorsal papillse mostly with cnidocysts, simple, not ramose nor furnished with a 

 cntaneoiis membrane; no crista between the rhinophores. 



A. Radula 0.1.0, the teeth horseshoe-shaped, usually not produced to a strong 

 spine ; papillse in regidar transversal rows : rhinophores simple, not laminated; 

 penis unarmed. 



1. Mandibular margin smooth; papillse more or less compressed; teeth of the 

 radula very broad, semilunar, with pectinated margin. Foot with lateral 

 angles in front or with short triangulär lobes (subfam. Aeohdinse). 



a. Teeth of the radula uniformly arched Aeohs Cuvier. 



h. Teeth of the radula incised in the margin Aeolidiella Bergh. 



2. Mandibular margin denticulated ; papillse subconical (subfam. Crateninse). 

 fl. Papillse in densely set rows; anus lateral; foot more or less rounded 



in front; mandibular margin with one row of denticles. 

 + . Teeth of the radula with marginal spines of varying size; foot broad, 

 rounded in front; head broad Cuthona Ålder & Hancock. 



+ + . Teeth of the radula with the margin pectinated (spines of uniform 

 size) ; foot shortly lobated in front : head of usual breadth 



Cratena Bergh. 



h. Papilke in dusters; foot with produced angles: anus latero-dorsal. 



+ . Mandibular margin witli inany rows of denticles Cutliouella Beegh. 



+ + . Mandibular margin « itli one row of denticles Hervia Beec-ih. 



B. Radula 1.1.1 with the central teeth produced in a strong spine ; papillse in 

 rows on regular obliquely - transverse ridges; rhinophores smooth; penis 

 unarmed, furrow-shaped; female genital aperture with a pair of aculeated 

 cushions (subfam. Ckimanotinse). 



Mandibular margin with one row of denticles; teeth of the radula dentated; 

 oral tentacles papilla-shaped : head much expanded laterally: anus latero-dorsal 



Cumanotus n. sp. 



C. Radula 1.1.1 or 0.1.0 v/ith the central teeth produced in a spine; papillse 

 mostly in dusters, in longitudinal series or in irregular transverse rows ; penis 

 armed or not. 



1. Rhinophores simple, rarely laminated. 



a. Anus latero-dorsal ; papillse clavate or inflated : foot rounded or with 



produced anterior angles (subfam. Tergipedinse). 



+ . Radula 0.1.0. 



a. Penis unarmed ; no glandula? ptyalinse. 



*. Papilla3 in one row on each side. intlated: foot rounded in front: oral tentacles 



present: mandi)3ular margin denticulated Tergipes Aldee lC: Hancock. 



**. Papilke in many longitudinal rows, inflated; foot with tentacle-shaped produced 



anterior angles; teeth of the radula united to a serrated l)and: uiandilralar margin 



smooth: no cnidocvsts Forestia Trfxchese. 



