27 



stomial thickenings are either quite confluent with the suboral areas of the adja- 

 cent zooecia or indistinctly divided from the latter. Sometimes there may be found 

 indistinctly defined tubercles between the zooecia of the same transverse series. 

 The aperture which is broader than high has a broadly rounded anter and a well- 

 developed sharply defined oral ledge which only decreases very little in heigth to- 

 wards the proximal margin. A very much convex operculum has only been found 

 in a small number of zooecia. The triangular flat suboral area is obliquely de- 

 scending towards the aperture. 



The Heterozooecia are very rare, and in each of the four fragments examined 

 which have a length of 12 — 20 '"™ they have only been found in a number of 

 1 — 4. They are more than twice as long as the zooecia and are of a similar form 

 as the heterozooecia figured in pi. II, fig. 19 and belonging to Mel. angulosa. The two 

 lateral margins, however, are much more incurved, and the aperture therefore is al- 

 most completely hour-glass-shaped, the two dilatations being about of the same form 

 and size and being connected by a very narrow median part, the breadth of which 

 is contained about four times in the breadth of the proximal margin. The suboral 

 area has the same form and size as in the zooecia. Each heterozooecium is bor- 

 dered by two pairs of zooecia, and those belonging to the distal pair has a similar, 

 but still more oblique position as in those seen in pi. 11, fig. 18. 



Ooecia have not been found. 



No Kenozooecia. 



The Closure takes place in great measure by the aid of a flat or somewhat 

 concave lamina placed at the rule at a much deeper level than the oral ledge. 



A Regeneration has not been found. 



The Colonies. I have examined four incomposite cylindrical fragments each 

 provided with 1—2 lateral branches. The zooecia, tlie apertures of which are gene- 

 rally placed very near to each other, are arranged in distinct transverse series, each 

 containing about 20 zooecia. 



Le Mans (Cenomanian). 



In the specimens examined a number both of the closure-plates and of the 

 opercula have undergone a more or less complete decalcification, and several of 

 these structures are represented only by thin chitinlike membranes, which are left 

 unaltered after a fragment has been dissolved in muriatic acid. 



Melicerititcs Caniii n. sp. 



[P\. Ill, figs. 20-27.) 



The Zooecia which are divided by distinct marginal ridges, are more or less 

 regular hexagonal, twice as long as broad, and the large about half-elliptical aper- 

 ture which only in its distal half takes up the whole breadth of the zooecium is a 

 little shorter than the concave or mostly saddle-shaped subopercular area which is 

 strongly ascending towards the well-developed peristome. The aperture is provided 



