Clithriellum inclusum Species
- Smittia inclusa Waters, 1904: pp.68-9, pl.IV, fig.5a-f.
- Smittina inclusa Canu & Bassler, 1920: pp.458-9, fig.132J-K.
- Clithriellum inclusum Rogick, 1956b: pp.70-4, figs.A-L.
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"Smittia inclusa sp. nov.
(Pl. IV, figs. 5a-f)
Zoarium cylindrical, branching dichotomously, with usually six zooecia in cross section, namely three full sized and three commencing. Zooecia elongate, distinct, with a row of fairly large pores surrounding the zooecia. The peristome is much elevated at the distal end, and at the proximal end there is a groove, leading down to an opening in the denticle, through which it passes. There is occasionally an avicularium with a semicircular mandible at one side just below the peristome. The ovicell is scarcely at all raised, but the portion above the aperture is somewhat inflated and is much larger than in the non ovicelligerous zooecia.
The zoarium is about 1 millim. in diameter; the lower zooecia are often quite closed, and the divisions of the zooecia are only indicated by the row of pores, whereas theyounger zooecia are very distinct and convex. The most interesting point about this species is the groove in the peristome and it is probable that the lyrula is formed by two denticles uniting, however it is not quite clear that this plate should be compared with the lyrula of Smittia, so that possibly this may have to be made the type of a new genus. The groove is similar to those in Retepora of which I wrote (2) « this pore is frequently the opening of a long tube, which runs down the peristome to the opercular opening ».
The avicularia are rare, and upon some specimens none are seen, for in looking through 40 colonies only four were found, also very few ovicells occur. The ovicell is subject to some variation, and the distal projection seen in the ordinary zooecia is more pronounced in the ovicelligerous zooecia, and may turn over the aperture, entirely covering it (fig. 5a (pr)). To show all the variations an entire plate would not suffice, but using camera lucida drawings for the shape and position of the zooecia and then representing characteristic zooecia, with ovicells and apertures in different positions, it is hoped that the varying conditions will be understood, though I must add it is not possible to give an absolutely correct view of the peristomial tube, as seen when looking down it.
There are two distal rosette plates with numerous pores, and the four lateral plates appear to be very similar, though from the preparations I cannot state the number of pores. Specimens 562, 610, 596 have been examined for polypides, but none have as yet been found, though there are a few buds.
This species is closely allied to Smittia (Vincularia) exarata of REUSS (1), and possibly it is that species, but in the fossil it is impossible to see the details of the aperture.
HABITAT. - Exp. Antarct. Belge.
Nos 562, 596, 1028, Tangles VII. Lat. 70º 23' S.- Long. 82° 47' W.; 480 met.; +0.8 C. Nos 610, 611, 621, 623, 650, 683, 991, Tangles VIII. Lat. 70º 00' S.- Long. 80º 48' W.; 500 ? met.; +0.9 C.
No 798, Tangles X. Lat. 700 15' S.- Long. 84° 06' W. ; 569 met. ; +0.8 C.
(2) Journ. Linn. Soc. Zool., vol. XXV, p. 256." (Waters, 1904: 68-9)
Exp. Antarct. Belge, Nos 562, 596, 610, 611, 621, 623, 650, 683, 991, 1028, Tangles VII, VIII, X
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