80S I'.EC'OKDS OP TIIK ArSTHALTAX MrSEFJM. 



Back arched. Border of the mantle not notched and without niiilticellular 

 glands. Branchial plumes sometimes present ; dorsal eyes present and usually 

 arranged in groups. 



Oncis. Hyponota as broad or broader than the sole of the foot. Head small 

 and almost always broadly over-reached by the head sliield. Form broadly 

 oval, elongate oval, or rounded ; back depressed. Mantle border not notched 

 and witliout multicellular glands. Branchial plumes absent. Dorsal eyes 

 when present not arranged in groups. 



Ta. Anterior portion of the jjeuis armed with cartilaginous hooks ; a cartilaginous 



tulie present Onrjiidiuni steeiistyupii, Semper. 



,, mannoratum. Lesson. 



,, ambiguuiH, Semper. 



,, vaigiense, Quoy & Gaimard. 



lb. Anterior portion of the penis armed with cartilaginous hooks ; posterior portion 



soft but with a cartilaginous element Onchidium vei-rHCidalitm. Cuvier. 



tnmidum, Semper. 

 ,, melanopnenmon, Bergh. 



peronii, Cuvier. 



Ic. Anterior portion of the penis snuioth, and without cartilaginous hooks ; a 

 cartilaginous tube present. 



II. An appendicular gland present, but cartilaginous element absent 



Onchidimn dauielii, Semper. 

 griseum, Plate. 



III. An appendicular gland alisent, but cartilaginous element present in the 

 penis. 



a. With small cartilaginous hooks only Onrltidimn nehnJosuni, Semper. 



1). With small cartilaginous hooks and tube Oncis coridceo, Semper. 



c. Anterior portion of the penis soft and without cartilaginous hooks ; a 

 cartilaginous tube present '. Oncis lata, Plate. 



d. Without hooks and cartilaginous tu))e, but with a small cartilaginous support 

 near the appendicular gland Oncjtidiiim cinerenni, Quoy &. Gaimard. 



IV. An appendicular gland and cartilaginous element absent 



OiirhiJi u in paimanum. Semper. 

 ,, nieriakrii, Stant. 



,, fangiforme, Stant. 



,, bentscJilii. Stant. 



Oncis chameleon. Brazier. 

 B. The male genital opening situated to the outside of the right tentacle. ■ 



Pemnina. — The hyponota ascend shar])ly from the foot. Body form oval. 

 Mantle border notched. Female genital opening situated I of the body length 

 anteriorly. Male genital 02)ening double. 



Oncliidina. — No hyponota. Form elongate oval, hack not strongly arched. 

 Mantle borders not notched. Head medium in size. Branchial plumes and 

 dorsal eyes absent. Tentacles incapable of retraction. Respiratory opening 

 to the right of the anus. 



OnchideUa. — Body form oval, back arched. Mantle border finely notched or 

 lobed, frequently with large cellular glands discharging at the apex of tlie 

 lobes. Head small. A slender longitudinal fold, or hyponotallina. runs from 

 the tentacle to the resjjiratory opening close to the foot border, and on 

 the riglit side rather near the foot groove ; the hyponotallina thus sejiarates 

 the hyponota into a liroad finely granulated outer zone and a smooth 

 inner zone. 'J"he foot groove runs ))ack\\ards to the anus, fusing with the 

 muscular anal ring. Bra.nchial jilumes and dorsal eyes absent. 



I. Appendicular gland, cartilaginous hooks and tuy)e present in the penis. 



II. Without an appendicular gland, but with cartillaginous hooks and tube 



present in the penis Onrjiidina riK.s^ahs, Semper. 



III. An appendicular gland and cartilaginous element absent 



OnchideUa initelloides, Quoy & Gaimai'd. 



