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that ovicells are formed so precociously as in L. verrucaria\ and it seems probable that they 

 are not as a rule produced until relatively late in the development of the colony, and that in 

 some cases they do not appear at all. There is here no indication of the extension of the 

 cavity of the ovicell by the addition of alveoli to its growing margin; and the cavity is frorri 

 the fïrst a continuous space, as shown in fig. 6. The present species agrees with L. verrucaria, 

 on the other hand, in its capacity for developing secondary ovicells, at a late stage in its growth. 



The variability in the appearance of the colonies appears to depend also on the extent 

 of the production of ovicells; but it is greatly affected by the varying development of the 

 cancelli. In colonies which have produced no ovicell, the central region is depressed; while 

 in fertile colonies this is usually the thickest part. 



The extent to which the radiating series of zooecia project is further a variable character. 

 In some cases, as in fig. 8, the rays are extremely prominent at their central ends, where 

 they may be biserial, with the peristomes of the two series diverging from one another and 

 to a considerable extent free. The more marginally situated zooecia diminish rapidly in height 

 to the outer border of the colony. In other cases, as in fig. ii, the rays project but little; 

 even the central zooecia being but slightly prolonged, and all the zooecia being arranged in a 

 sinsfle radial series. The extreme modifications are so different from one another that, in the 

 absence of other evidence, the specimens might well be referred to two species. But, on the 

 other hand, colonies from the same dredging may show both these extremes, with other 

 individuals which are intermediate. I have been unable to make any satis'factory division of 

 the specimens on the basis of the difference between the projection of the peristomes; and it 

 appears to be necessary to regard this character as one which is really very variable. The 

 zooecia are commonly compressed, the peristomes having a corresponding form, and being 

 often produced into a point on the marginal and on the central side. 



The form of the roof of the ovicell is another feature which is subject to variation. 

 Fig. 9 shows a colony in which the roof has probably been broken. The Moor is thus exposed 

 and is seen to be composed of a smooth calcareous film which has overspread the underlying 

 cancelli; a few pores, not represented in the figure, leading through the floor of the ovicell 

 into the cancelli. The part of the roof which is complete is seen to be composed of two very 

 convex lobes which are thickly covered by pores. These lobes are seen through the openings 

 of large cancelli which have been developed superficially to the roof of the ovicell. 



Fig. i i shows a very different condition ; the lobes of the ovicell being here roofed by 

 a nearly fiat calcareous lamina, which is covered by pores. This specimen, taken by itself, might 

 well be regarded as a distinct species ; but those shown respectively in fig. 6 and fig. 8 are 

 from the same dredging and agree closely with one another in other characters; while they 

 show the two conditions of the roof of the ovicell which have just been indicated. The younger 

 specimen (fig. 6) has two distinct ovicells, of which the one on the lower side of the figure 

 has at present no roof, but its floor is similar to that of the specimen shown in fig. 9 and 

 already described. The ovicell of the upper side has a roof which consists of a narrow, flat, 

 perforated lamina, which is not unlike that of fig. 11. In fig. 8, from the same Station, 

 the growth of the ovicell is nearly complete; but its roof, seen through the widely open 



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