DESCEIPTIONS OF THE SPECIES. 179 



it may be stated generally thai this poini will separate P. Wachamuthi from all 



species of the genus known to ns. In some respects it is not unlike /'. Americana, 

 BarriSj but it lacks the wide radial Binuses of that type, specimens are frequently 

 met with broken short oft' at the basiradial suture, when, if care be not taken, the) 

 might at a casual glance be mistaken for examples of Granatocrinus. 



It affords ns very great pleasure to name this species after Mr. Charles Wachsmuth, 

 to whom we are greatly indebted for most valuable assistance in our study of the 

 Blastoidea. 



Locality and Horizon. Colle, near Sabero, Province of Leon, Spain : Calcaire 

 d'Amao, Lower Devonian. (Presented by Dr. P. II. Carpenter, F.B.S.) 



Pentbemitidea Gilbertsoni, sp. nov. 

 (PL V. figs. 9-11.) 



Sp. Char. Calyx obtusely clavate, suddenly enlarging upwards above the basi- 

 radial sutures; summit small, contracted, and considerably hollowed; peristome very 

 concave ; periphery nearly equatorial, rather nearer the summit than the base. Base 

 triangular and tricarinate, with the sides flattened, or slightly concave. Basal plates 

 convex or arched above, carinate below, forming a strong expanded cup ; interbasal 

 sutures in slight concavities. Eadial plates large, oblong, their surfaces in two 

 planes which cut one another at a line drawn through the radial lips ; the lower 

 portion or body of each plate is small and concave, the limbs are long and much 

 arched ; sinuses narrow, sides subparallel and a little thickened ; lips prominent ; 

 interradial sutures in slight concavities. Deltoid plates quite small, assisting to form 

 the contracted summit, and just visible in a side view. Ambulacra much curved, 

 quite half the length of the calyx, projecting above the edges of the sinuses ; lancet- 

 plates just visible in the median line for about half the length of the ambulacra; 

 side plates from twenty to thirty ; pores large. Hydrospires unknown ; spiracles large, 

 oval pyriform. Column and ornament not preserved. 



Remarks. This species is remarkable from the sudden inflation of the calyx imme- 

 diately above the basiradial sutures. Owing to this character and to the length of 

 the curved ambulacra it has a top-heavy appearance. There is a certain amount of 

 resemblance between P. Gilbertsoni and P. angulata (PL IV. figs. 13, 14), but one 

 is pentagonal in section and the other decagonal. The inflation of the calyx in 

 P. acutangula is greater than in the present species, and its base is also smaller ; 

 but there is much resemblance between P. Gilbertsoni and a very young P. clavata 

 figured by Schultze l . AVe name this interesting species in memory of one of the 

 earliest collectors of British Blastoids. 



Locality and Horizon. Colle, near Sabero, Province of Leon, Spain: Lower 

 Devonian. (Presented by Dr. P. H. Carpenter, F.R.S.) 



1 Denkschr. k. Akad. Wisaensch. Wien, 1SG7, BJ. xxvi. Abth. 2, taf. xiii. fig. 7c. 



•1 A 2 



