GLOSSARY 



393 



inter op er cular , the posterio-inferior 

 opercular bone of fishes, 232. 



jugal, the cheek-bone, 232. 



keel, a ridge on the breast-bone of 

 birds for attachment of flying mus- 

 cles, 314. 



labial, pertaining to the labium. 

 labium, the under lip of insects, 59. 

 labrum, the upper lip of insects, 59. 

 lamella, a leaf or plate, 58. 

 lamina, a thin plate. 

 lancet cell, a lancet-shaped cell on the 



hinder margin of the fore wing of 



Phytophaga, 43. 

 larva, an immature but active stage of 



development, 10. 



ligula, the front edge of the labium, 59. 

 liver area, in crabs, the anterio-lateral 



area of the carapace in front of the 



gill region, 123. 



lumen, the central space of a tube. 

 lunule, a crescentic or heart-shaped 



area in front of the beak of some 



bivalve shells, 190. 



madreporic plate, in echinoderms, a 



perforated plate admitting water to 



the system of water tubes, 204. 

 mandible, in arthropods, the most 



anterior of mouth parts, 59; in 



vertebrates, the bone of the lower 



jaw. 

 mantle, the fold of the skin of a mol- 



lusk, or cirriped, which secretes the 



shell, 160. 

 manubrium, in jelly-fishes, the mouth 



stalk, corresponding in position to 



the clapper of a bell, 211. 

 marsupium, a pouch, in Marsupalia, 



on the ventral side of the body, 



331. 



maxilla, in Arthropoda, one of the 

 mouth parts immediately following 

 the mandible, 59 ; in vertebrates, a 

 tooth-bearing bone of the upper jaw. 



maxillary, relating to the maxilla. 



maxilliped, one of the foot-like mouth 

 parts which in arthropods follow 

 the maxillae. 



mentum, the front plate of the labium 

 in insects, 59. 



mesopterygoid, one of the bones form- 

 ing the base of the skull in bony 

 fishes, 232. 



mesothorax, the middle segment of the 

 thorax, 59. 



metamerism, the fundamental repeti- 

 tion of parts of the body along the 

 longitudinal axis, as in earthworms 

 139. 



metapleure, in Amphioxus, a latero- 

 ventral fin, 249. 



metapterygoid, one of the bones form- 

 ing the base of the skull in bony 

 fishes and lying behind the mesop- 

 terygoid, 232. 



metasternum, the ventral plate of the 

 last thoracic segment of insects, 59. 



metatarsus, in birds, the foot proper, 

 315. 



metathorax, in insects, the third or 

 last segment of the thorax, 59. 



morula, an early stage of egg develop- 

 ment when the germ consists of a 

 nearly solid mass of cells, 336. 



moult, to change the skin, as in in- 

 sects. 



myocomma, the thin layer separating 

 two muscle plates in vertebrates, 246. 



myomere, a muscle plate, 246. 



nasal, belonging to or forming the 



nose, as nasal bones. 

 neural, pertaining to the nervous 



system. 



