. The Australian zoologist. Zoology; Zoology; Zoology. IREDALE AND IIFLL. 309. Fig. 4.—Loricate animal, as dried in shell. (When alive the foot is generally more expanded, hiding the gills). H.—Head, M — Mouth, F.—Foot (ventral surface), G.—Gills. The Animal.—The ventral surface of the Lorieates consists of a fleshy foot, similar to that of the Gastropoda. Anterior to the foot is the head, with the mouth in the centre. The gills extend along and behind the edges of the foot from one-fourth to the entire length of the foot; commencing at the posterior end. The distinguishing feature of the Orde
. The Australian zoologist. Zoology; Zoology; Zoology. IREDALE AND IIFLL. 309. Fig. 4.—Loricate animal, as dried in shell. (When alive the foot is generally more expanded, hiding the gills). H.—Head, M — Mouth, F.—Foot (ventral surface), G.—Gills. The Animal.—The ventral surface of the Lorieates consists of a fleshy foot, similar to that of the Gastropoda. Anterior to the foot is the head, with the mouth in the centre. The gills extend along and behind the edges of the foot from one-fourth to the entire length of the foot; commencing at the posterior end. The distinguishing feature of the Order is the symmetrical arrangement of the internal anatomy, all other Gastropods being asymmetrical in this respect. While there are no tentacles or eyes in the adult, many species have visible ocelli in the tegmentum, which are connected with the nerve-centre and are functional in conveying to the animal the sensation of light or darkness. Even where these ocelli are not visible, the animal is sensitive to light, and endeavours to escape from it. The radula, the organ by means of which Lorieates obtain their food, consists of a long siliceous ribbon bearing numerous rows of hooklets, and as this is the only hard part of the internal anatomy of most mollusks it has been largely used in grouping. In the Lorieates the radula, odontophore, or lingual ribbon, as the organ is variously called, is of a complex type and can only be used by a specialist familiar with microscopic work, requiring long and careful study. As it is easily seen with the naked eye near the head when Lorieates are being cleaned out, we may note the general features as follows:—Viewed with a lens it presents a spiny surface, the spines arranged in rows of about 16, two near the middle being much larger and more strongly hooked than the others. The total length of the radula may, in the larger Lorieates of the Region, measure 10 mm., with a breadth of 1 mm. It is used to tear away the algal or fleshy
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1914
