270 



NEW GENERA AND SPECIES 01-' CYSTIDEA. 



[1854. 



Comarocystitcs punttttahis. 



Fig. 1. Side view of a specimen separated from the matrix, a— position 



of the ovarian aperture. 

 Fig. 2. Tlie summit showing the direction of the supposed mouth with 



. respect to the ovarian aperture. 

 Fig. 3. A large specimen of Comarocystiles punctuatus, retaining an arm 

 and several tentacula. The dotted lines on the right show the impres- 

 sion of another arm. The plates of the ovarian aperture are restored 

 in the figure. They are shattered in the specimen. 

 The general form of this species is somewhat oval, projectinglargely 

 on the ovarian side. Its greatest expansion is near the summit, 

 whence it tapers to a point at the base" of the diameter of the column 

 or a little longer. The plates are deeply depressed in the centre, 

 and thus the whole surface is covered with almost hemispherical 

 pits, except near the base, where the small plates are but slightly 

 concave. The surfaces of the plates are covered with small oblong 

 punctuations. If lines be drawn from the centre of each plate to 

 each of its angles, they will divide it into as many triangular 

 spaces as it has sides. All the oblong punctuations in each of 

 those spaces will be found parallel with each other, but not with 

 those of the adjoining spaces. They are arranged in rows parallel 

 to the edges of the plate, and the greatest axis of each pore is at 

 right angles to the suture. In this respect they correspond to the 

 striation usually seen on the plates of the Cystida?, which gene- 

 rally cross the sutures at right angles from the centre of one plate 



to that of another. They do not penetrate but to a short distance 

 below the surface, and when tl i* ? plates are weather-worn they 

 disappear altogether. On each of the ridges which mark the po- 

 Mti"i,~ ( ,f lln- Miiuivs 1.,-twc-n the plates, there is a single row of 

 those pores which penetrate deeper, and arc seen after they have 

 been worn away from the interior of the plates. Nearly all the 

 specimens have this character of surface. In the large one, how- 

 ever (Fig. 3), a small space in the depressed centres of each plate 

 is smooth, and from the border of this space lammellar ridges 

 cross over to the adjoining plate. These ridges are divided by 

 other ridges crossing them parallel with the sutures. The effect 

 produced is nearly the same. Near the ovarian aperture, also, in 

 this specimen, from the bottom of each of several of the cavities 

 arises a rough tubercle to the height of the surrounding ridges. 

 Other individuals differ slightly in their surface markings, but 

 perhaps only sufficient to constitute varieties. The specimen, Pig. 

 3, is crushed, and does not exhibit the true natural shape. A very 

 large specimen pressed quite flat, and lying on a slab of limestone, 

 h;is a portion of the upper side removed, so that the interior sur- 

 face of the side below can be seen. The plates are thus found to 

 be on their inside elevated in the centre, and covered with strong 

 rounded ridges, radiating to the centres of the sides. They do 

 not extend to the centres of the plates, but cross the furrows made 

 on the inside by the elevation of the borders of the plates on the 

 outside. The pelvic plates are low, broad and serrated on their 

 upper sides. They are so firmly united to the upper joint of the 

 column and to each other, that it is difficult to detect the division 

 lines between them. 



GENUS AMYGDALOCTSTITES. 



This very curious and beautiful Cystidean differs from the for- 

 mer principally in the manner in which the arms are constructed. 

 They are not free or springing upwards like the arms of a Crin- 

 oid, but consist of a short row of calcareous joints crossing the 

 summit, and extending a short distance down the sides. From 

 each of these joints a long tentacle arises, similar to those of the 

 last species. As the specimens are deeply embedded in the rock, 

 very little can be said about them at present The most perfect, 

 Fig. 4, much resembles an almond, and I therefore propose for it 

 the generic name Amygdalocystites. Its characters, so far as they 

 can be determined, are as follows : — 



Body ovate, pelvis of three ( ?) plates, above which are eight or 

 more rows of plates, completing the cup, ovarian aperture near the 

 summit, closed by a valvular apparatus, arms composed of a row 

 of joints crossing the summit and articulated to the surface, each 

 joint bears a tentacle, column round and of thin joints, mouth un- 

 known. 



Amygdalocystites florealk. 



Fig. 4. 



Fig. 5. 



