4 BULLETIN 60, UNITED STATES NATIONAL MUSEUM. 



bhb. Valves 8, all with apical uinbones, and finely t-renated lines of jjrowth, the 

 scuta, terga, and carina large, rostrum ami one pair of latera small; peduncle 

 covered witii small scales, those of the upper row crenated; terminating at 



the base in a calcareous cup or row of disks _ Genus Lithotrya. 



Ml. Unibones of scuta and terga apical, no other valves present; peduncle covered 



with chitinous spines Subfamily InLiNiK. 



I). A'alves 4; characters those of the subfamily (xenus Ibla. 



(Kia. Valves 5; terga, scuta, and carina large, the latter two having umbones 

 slightly above the middle of the plates; carina angularly bent; peduncle 



with calcareous spines Subfamily Oxynaspidin^. Genus Oxynuspis. 



aaaa. Valves 3 to 5; carina with the two ends unlike, the umbo basal or below the 

 middle; umbo of scutum at or near the rostral angle; caudal appendages one- 

 jointed; peduncle nude Subfamily LEPADiNiE. 



b. Plates fully calcified, approximate. 



c. Carina extending upward between the terga; one or more lateral filaments at 



bases of first cirri; caudal appendages smooth Genus Lepas. 



cc. Carina extending to the base of the terga, truncate at base; no lateral fila- 

 ments; caudal appendages spinose. 



d. Carina narrow throughout Genus Pcecilasma. 



(id. Carina with wide sides toward the base Genns Megalasma. 



bb. Plates incomi^letely calcified, the hard portions separated by wide chitinous 

 spaces; scutum calcified in two or three diverging branches; carina termi- 

 nating below in a disk, cup, or fork at the base of the capitulum. Valves 5 



or sometimes apparently 7 Genus Odolasmis. 



aamia. Valves wanting, or greatly reduced, widely separated and inconspicuous, scuta 

 Avhen present with the umbones near the middle of the occludent margin. 



Subfamily Alep.adin^. 



b. Valves 2 to 5, very small; carina, when present, with the upper and lower ends 



nearly alike; lateral filaments at bases of first pair of cirri; caudal appendages 



wanting. Living attached to floating objects Genus Conchoderma. 



bb. Only a pair of vestigeal scuta developed; integument thin, without internal 

 muscular layer; cirri unusually short, composed of few joints; caudal appen- 

 dages one-jointed. Living attached to medusas Genus Alepas. 



bbb. Capitulum wholly without plates, or with a pair of vestigeal scuta, a muscular 

 layer underlying the integument; cirri long; caudal appendages well devel- 

 oped, composed of several spinose segments. Living attached to objects on 

 the bottom Genus Heleralepas. 



Genus MITELLA Oken. 



1815. Mitella Oken, Lehrbuch der Zoologie, I, p. 362, for Lepas pollicipes. 



1817. Pollicipes Leach, Journal de Physique, LXXXV, p. 68, July, 1817, no 



type mentioned. 

 1851. PoUkipes Dakwix, ^Monograph on the (^irripedia, }). 293, and of authors. 

 1904. Vaucheria Pallary, Journal de Conchyliologie, LIT, p. 7. 



It is much to be regretted that Darwin allowed the general use of the 

 name I*o/licij)es to influence his course in rejecting the earli(>st generic 

 name for this group, contrary, as he writes, to the rules of the British 

 Association. Had he accepted the earliest name, it would long ago 

 have become universall}' current. As matters .stand we have no option 

 but to use the generic tei'ui Mitella^ which Darwin himself showed to 



