212 SYSTEMATIC ARRANGEMENT 



21. G. reticulata, t. 64. f. 7. 



22. G. elegans, t. 64. f. 9. 



23. G. lineata, t. 220. f. 4. 



2. Brachychlanis. 



Body prismatic. Mantle small, slightly margined. Tentacle in 

 front of mantle. Teeth ? 



1. B. pantherina, Ehrenb. 



** Mantle edge bearded. 



3. Idalia. 



Body oblong, convex, smooth. Head much produced in front, 

 plain, thick. Mantle very small and indistinct, margined with a 

 semicircle of beards, largest in front of the tentacles. Tentacles 

 two ; dorsal linear, laminated, with a simple appendage in front, 

 but distinct from them. Gills simply pinnate, non-retractile. Lin- 

 gual membrane narrow, with four series of spines, the two central 

 series larger ; no central spine ; buccal collar spinose. 



1. I. elegans, t. 199. f. 10. 



2. I. cirrigera, t. 231. f. 1, 4. 



3. I. aspera, t. 215. f. 2. 



4. I. quadricornis, t. 223. f. 2. 



5. I. dubia, t. 232. f. 6. 



6. I. Lessonii, t. 204. f. 9, t. 274. f. 3. 



7. I. insequalis, Forbes #• Hanley,B.M. t. V.V. f. 4. 



Ceratodoris eolida, t. 67. f. 5, is supposed by Mr. Alder to be a 

 young Idalia. 



"The centre of the back of I. elegans with filaments. Lingual 

 spines next the centre falcate, and smooth, or minutely denticulated ; 

 external spines short ; spinose collar complete." — Alder. 



" The centre of the back of I. aspera without filaments. Lingual 

 spines next the centre recurved and strongly denticulated ; external 

 spines much hooked ; spinose collar incompletely bilobed." — Alder. 



Fig. 116. — Teeth of Idalia cirrigera. 



" Central tooth of Idalia cirrigera none ; lateral teeth two, first 

 very large, scape produced on both sides, longest on the outside, tip 

 clavate, armed with an incurved sharp point, serrated on the inside 

 (fig. 116)."— LovSn. 



