. A textbook of invertebrate morphology [microform]. Invertebrates; Morphology (Animals); Invertébrés; Morphologie (Animaux). TYPE MOLLUSC A. 327 le of the bling thft ranchia,. laajority jilateral d. The 'o large on each [ extend- e a wide and the and the jntacles, ly cases ipletely, exit of usion of thus in in Unio mantle- Is are in ;ent two he exha- and the le lower ; in the ese two nitact ( f of these 3xam])Ie, ,1 to the 'd a con- re three inication >t is pro- traded, and two posterior, the branchial and anal openings. The mantle around these latter frequently becomes prolonged so that t
. A textbook of invertebrate morphology [microform]. Invertebrates; Morphology (Animals); Invertébrés; Morphologie (Animaux). TYPE MOLLUSC A. 327 le of the bling thft ranchia,. laajority jilateral d. The 'o large on each [ extend- e a wide and the and the jntacles, ly cases ipletely, exit of usion of thus in in Unio mantle- Is are in ;ent two he exha- and the le lower ; in the ese two nitact ( f of these 3xam])Ie, ,1 to the 'd a con- re three inication >t is pro- traded, and two posterior, the branchial and anal openings. The mantle around these latter frequently becomes prolonged so that two tubes, or siphons as they are termed, are formed, sometimes in contact with one anotlier (Pholas), sometimes quite separate (Fe/iws), sometimes capable of retraction within the shell, sometimes so large as to be incapable of retraction (Mya).. Fig. 147.—^, Mya nrenaria with the siphons slightly expanded; B, inner sur- face of the riglit valve of the shell of Mi/<i. aa = impression of anterior ad- pa = impression of posterior -A- dnctor muscle. d„ctor muscle. I = ligament. pi = p,iiii,ii Hue. wi = mantle edge. « = siphon. ^ = '^'^"'" »i = si|)h()nal impression. In conformity with the form of the mantle-lobes the shell consists of two simihir portions or valves, lying on the sides of the body and united along the mid-line by a hinge. The hinge is formed by a ligament, as it is termed, which is really a portion of the shell substance, and consists of an external portion continuous with the <'))idernns of tlio shell and an internal elastic portion, frequently calcified to a cer- tain extent, and continuous with the middle layer (prismatic -aypr^ a, tno ^iieli. tr tu-u at rest the two valves of the sheii are kept apart along the ventral lino by the elasticity of the hinge-ligament, and it is only by the a[)plicati()n of force that. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readabi
Size: 1675px × 1491px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyo, bookyear1896
