. Zoology for high schools and colleges. Zoology. This suborder presents a beautiful series of increasingly complex forms, as we ascend from Limnetis to Branchipus. In Limnetis the bivalve shell encloses the ani- Aj mal, and is the size of a small flattened pea. There are from ten to twelve feet - bearing segments. L. Gouldii Baird (Fig. 238) is very jjV rare in Canada and New England. The shell Jfly of Limnadia is thin, oval, and there are from i/y eighteen to twenty-six feet-bearing segments. \ ii L. {Eulimnadia) Agassizii Packard (Pig. 339) inhabits small pools in Southern New En- gland. Th
. Zoology for high schools and colleges. Zoology. This suborder presents a beautiful series of increasingly complex forms, as we ascend from Limnetis to Branchipus. In Limnetis the bivalve shell encloses the ani- Aj mal, and is the size of a small flattened pea. There are from ten to twelve feet - bearing segments. L. Gouldii Baird (Fig. 238) is very jjV rare in Canada and New England. The shell Jfly of Limnadia is thin, oval, and there are from i/y eighteen to twenty-six feet-bearing segments. \ ii L. {Eulimnadia) Agassizii Packard (Pig. 339) inhabits small pools in Southern New En- gland. The shell of Estheria (Fig. 241, Es- tlieria Belfragei Packard) is sometimes mis- leg of male ^siAc-taken for that of the fresh-water moUusks nns. a. hand; *, Cyclas and Pisidium. The males of the fore- " ° ° ^' going genera have the first pair of feet modi- fied to form large claspers (Fig. 240). In Apus the abdomen projects beyond the large carapace, and ends in two long many-jointed appendages. There are about sixty pairs of feet, each foot divided into several leaf-like lobes, wherein respiration is carried on. These Phyllopods usually swim upon their backs, as in the species of Bran- chipus. The females chiefly differ from the males in the presence of an orbicular egg-sac on the eleventh pair of feet, the sac being a modification of two of the lobes of the feet, and containing but a few eggs. Apus mqualis Packard (Pig. 242, Fig, 244 A, represents the larva of a European Apus) inhabits pools in the western plains. Lepidurus differs from Apus in having the telson spoon-shaped instead of square. L. Couesii Packard (Pig. 243) occurs on the Rocky Mountain plateau in Utah and Montana. It is an interesting fact in zoo-geography that there are no species of Apus and Lepidurus east of the west- ern plains. Apus has been found by Siebold to reproduce parthenogenetically. The various species of Branchipus &nd Artemia have no. Kg. 241.—Shell ot Estheria Belfragei, enlarged
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Keywords: ., bookcentury1800, bookdecade1880, bookpublishe, booksubjectzoology
