Text-book of comparative anatomy . B are joined by a hinge is dorsal in the mussels, in the Brachiopoda itis posterior. We have already, inthe systematic review, saidwhat is most important con-cerning the oral tentaclesand oral arms, which arevery characteristic of theProsopygia • the variouspositions of the anus werealso described. Referto it also for the outerform and organisation ofthe Piotatoria and FIG. 125.—Rhynconella , From above. B, From the left side. II. The Integument. The integument of the worms consists first of the outer cuticle, andsecond of the subja
Text-book of comparative anatomy . B are joined by a hinge is dorsal in the mussels, in the Brachiopoda itis posterior. We have already, inthe systematic review, saidwhat is most important con-cerning the oral tentaclesand oral arms, which arevery characteristic of theProsopygia • the variouspositions of the anus werealso described. Referto it also for the outerform and organisation ofthe Piotatoria and FIG. 125.—Rhynconella , From above. B, From the left side. II. The Integument. The integument of the worms consists first of the outer cuticle, andsecond of the subjacent body epithelium, which secretes the cuticle, andwhich in most worms (just as in the ArtJvropoda) is called the hypodermis. The cuticle is very variously developed. It is thin and delicate inthe soft-bodied forms, especially in the Nemertina, where it is perforatedby very fine pores to allow the cilia to pass through. Where it isstrongly developed, as in many Annulata, Prosopygia, Nematoda, andPiotatoria, it gives protection and support to the body, and as skeletonoffers support and surfaces of attachment to the body musculature. Itconsists of a substance allied to chitin, and occasionally calcifies (inBryozoa, Brachiopoda) into a very hard envelope or shell. It oftenshows stratification, and seems to be composed of various crossingsystems of very fine adhering fibrillce. It may in general be conceivedof
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanatomycomparative
