SUPPLEMENT TO DECADE VIII. 



The delny which has occurred in the publication of tliis Decade has 

 been so far fortunate, that in the interval which has elapsed since the 

 completion of the manuscript, several specimens have been discovered, of 

 species described therein, substantiating the characters already given, and 

 supplying others which were deficient in the materials originally examined. 

 As several of the species were founded upon single specimens, it is of con- 

 sequence that the opportunity of recording this additional evidence should 

 not be lost, although it would not be advisable to incorporate it in the 

 descriptions completed two years since, and which are now in type. 



Article V. Plate V. 



Tlistionotus angularis. — This genus and species was determined by a 

 single specimen, in my own collection. The Museum of Practical Geology 

 has now two specimens of the genus, one of which belongs, no doubt, to 

 the same species. The other is a portion of a much larger fish, and may 

 possibly indicate a second species, but it is too imperfect to afford any 

 reliable evidence of distinctive character. Both these specimens are from 

 the Swanage quarries. 



Article VI. Plate VI. 



Aspidorhynchus Fisheri. — The British Museum and the Museum of Prac- 

 tical Geology now possess good specimens of this species. The original 

 of Plate 6 is so perfect, that no further evidence was necessary to complete 

 the specific description. 



Article X. Plate VIII. 



Ptycholepis ciirtus. — This species depended on the evidence of a single 

 specimen, in the possession of Mr. Beccles. A second specimen has recently 

 been sent to me from Lyme Regis (whence the first was also derived), 

 showing some details which were wanting in the one originally described. 

 The pectoral fins are here preserved. They are composed of from 18 to 

 20 rays each. These are strong, and closely arranged. They are single as 

 far as they are preserved, and show no transverse articulations. The 

 anterior margins of these fins were bordered. The ventral fins are placed 

 nearer to the pectoral than to the anal fins. They are small, and composed 

 of 10 or 12 slender articulated rays ; the articulations only commencing 

 near the extremities. The caudal fin contains about 20 rays in the upper^ 

 and 30 in the lower lobe. The former is strengthened by a ridge of elon- 



a 



