PLATE V. 



Fig. 1. Platyckinus laciniatus. a, b, c. 



a. — lateral view of specimen. 

 b. — dorso-central aspect, 

 c. — lateral view. 



Fig. 2. Platycrinus mucronatus. (variety) 

 a. — lateral aspect of P. mucronatus. 



Since the publication of our first Number, we have had opportunities of examining 

 Mr. Gilbertson's collection, in which we have found this interesting variety of the 

 P. mucronatus. Several figures of this species have already appeared in our second plate. 

 b, c, d. — Three specimens of the same species in their young state, shewing the points 

 on some of the abdominal plates prolonged into spines. It appears that when these 

 points are as much developed on a portion of the plates as those represented in the 

 figures, they are wholly wanting, or are merely rudimentary on the others. The 

 situation of the lateral mouth is very plainly exhibited in fignre d. 



Fig. 3. Malformed Platycrinus. a, b. 

 a. — view of abdominal cavity. 



b. — lateral aspect exhibiting the malformation, where the perisomic plates appear to rest 

 on the column. 



Fig. 4. Radical portion of a Platycrinus. 



Fig. 5. DicHocRiNUS radiatus. a, b, c, d. 

 a. — lateral aspect of D. radiatus. 

 b. — dorso-central aspect, shewing the division. 



c. — lateral view of a larger specimen exhibiting the non ray-bearing plate. 

 d. — the non ray-bearing plate. 



Fig. 6. DicHOCRiNUS fusiformis. a, b, c, d. 

 a. — enlarged lateral view. 



b. — natural size of the same specimen! with the rays attached, 

 c. — main ray and its bifurcations. 



d. — magnified lateral aspect, exhibiting the non ray bearing plate, and the dorso-central 

 division. 

 The specimens of Dichocrinus from which our figures are taken, are in the museum of 

 the Bristol Literary and Scientific Institution. 



