. Conspectus crustaceorum, quae in orbis terrarum circumnavigatione. Crustacea. and 4M. In a still further subdivision, each of the areolets is reduced to tubercles, some of them consisting of'but one, and others of three or four. Figure 4 represents the medial region of the Lngostoma nodosa; the prsemedial is a single tu- bercle; the extra-medial consists of 7 tnbercles, 3 in an inner and 4 in an outer series ; the intra-medial includes 4 besides some smaller; and the post-medial inckides 2 large and some smaller tubercles. When the subdivisions are not carried as far, a portion may be separa
. Conspectus crustaceorum, quae in orbis terrarum circumnavigatione. Crustacea. and 4M. In a still further subdivision, each of the areolets is reduced to tubercles, some of them consisting of'but one, and others of three or four. Figure 4 represents the medial region of the Lngostoma nodosa; the prsemedial is a single tu- bercle; the extra-medial consists of 7 tnbercles, 3 in an inner and 4 in an outer series ; the intra-medial includes 4 besides some smaller; and the post-medial inckides 2 large and some smaller tubercles. When the subdivisions are not carried as far, a portion may be separated anteriorly from each half of 2M, while the rest remains entire. It is coramon for ]R to have a tubercle or two on its snrface or areolets in the same transverse Hne with ihe tooth. Teeih of the antero-lateral rnargin.—The teeth of the margin are normally^?;e in number, commencing with the post-orbital as the first. These five are represented in figure 1, and are desig- nated m order by the diflferent letters of ihe word dentes (or detits in French) D, E, N, T, S. Each tooth is often separated from the adjoining by a minute suture at the bottom of ihe indentation between ihem, and hence the letters always marii rather a lobe of the margin than simply a tooth. These teelh vary by obso- lescence or subdivision, lil^e the areolets. Iq obsolescence, the tooth E (second) is the first to disappear, this reducing the apparent number tofonr. Then N fades out, then T, leaving S alone which may also be wanting. Again S is sometimes smaller than T and even disappears. In the m,iiltiplication of teeth, there is often, as a first addition, a tooth s' (or two s'. s",) posterior to S. Ttiere is often also a tooth {d') between D and E on a lower level than D. But the multiplication is generally dependent on the subdivision of the normal teeth E, N, T, in addition sometimes to S and D,—each of these leeth consisting of two or three teeth, either all equal or one more prominent. In o
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Keywords: ., bookcentury1800, bookdecade1840, booksubjectcrustacea, bookyear18
