. A text-book of invertebrate morphology. Invertebrates. TYPE CRUSTACEA. 397 tially parasitic, still retain more or less perfectly tlie segmen- tation and general appearance of free-swimming forms, the modifications which they have undergone affecting principally the antennae, which are modified for purposes of adhesion to the host, the mandibles, which are piercing organs, and in some cases the maxillae, which may, like the antennae, become hook- like. Frequently, however, the body assumes aberrant forms, as in Fhilichthys (Fig. 178, A), and the segmentation may en- tirely disappear, as in Fe
. A text-book of invertebrate morphology. Invertebrates. TYPE CRUSTACEA. 397 tially parasitic, still retain more or less perfectly tlie segmen- tation and general appearance of free-swimming forms, the modifications which they have undergone affecting principally the antennae, which are modified for purposes of adhesion to the host, the mandibles, which are piercing organs, and in some cases the maxillae, which may, like the antennae, become hook- like. Frequently, however, the body assumes aberrant forms, as in Fhilichthys (Fig. 178, A), and the segmentation may en- tirely disappear, as in Fenella, Lerncea, Chondracanthtcs, Achtheres (Fig. 178, £), and Anchorella, these last two forms presenting a peculiar modification of the second maxillae in the females, the two appendages fusing at their tips to form a chitinous adhesive disk which serves as an organ of adhesion. In the majority of these forms, as already noted, the thoracic appendages may become more or less rudimentary; indeed even in the less modified forms, such as Ergasilus, the appendages of the fifth thora- cic segment may be wanting. 3. Suborder BrancMura. In the Branchiura the cephalic and thoracic seg- ments are fused together to form a shield-shaped cephalo- thorax, while the abdomen is small and divided into two platelike halves which have a rich blood-supply, appar- ently serving respiratory pur- poses, and in the males contain the testes. The basal joint of the an- tennules (Fig. 179, at') is devel- oped into a strong hooked process, and the mandibles and first maxillaB, which are stylet-like, are enclosed ia a tube. Fig. 179.—Argulus foliaceus Glaus). at' = antennules. I = digestive gland- ma; = second maxilla. oc= eye. t = testis. (after. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original McMurrich, J. Playfair (James Playfai
Size: 1219px × 2049px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyo, bookyear1894
