HI 



The skeleton of a Plaice (Plftirotcctet Plateiua). The number of the abdo- 

 minal and caudal vertebra agrees with that in the preceding skeleton. 



MM. SoiitJi. 



181. The last abdominal and several anterior caudal vertebra; of the Plaice (Pleura- 

 neck* Plate&a). 



The distinctive character of the caudal vertebrae u shown by the deflection and coaleaefM* 

 of the parapophyses, to form the haemal canal. Both neural and haemal spines are of greet 

 length : the first and tecond haemal arches and spinet have coalesced at their proximal halve*, 

 a abort transverse process if tent out frum the baae of the second caudal parapophysis, and 

 from the sides of the centrum in the succeeding caudal vertebra-. 



Two interneural spines are attached to the summits of each of the four anterior neural spiur*. 

 and two interhaemal spines to the extremity of the third haemal spine in this specimen. 



Jlunterian. 



!-.' The skeleton of the Halibut (Pleuronecfet J/ippoylosau, Linn.; IHppogliixxu* 

 vulyaris, Cuv.). 



It shows on a large scale the wwyni metrical modification of the bones of the head in the 

 Plevronrttitlit. This is peculiarly manifested in the frontal, postfrontal, prefrontal, nasal 

 and vomerine bones : only one orbit is completed, namely the right, by the great develop- 

 ment and complete ossification of the suborbital bones, which are firmly connected by suture 

 with the prefrontal and postfrontal bones. The arrangement of the teeth is less unsym- 

 iiu-t rical than in the Plaice ; there being as many teeth on the right premaxillariea and pre- 

 niandibulars as on the left : they are all conical, recurved, and sharp-pointed. The branchial 

 arches and pharyngeal bones support similarly shaped teeth. The parapophy sea progres- 

 sively increase in length, bend down and unite at the seventeenth vertebra, where they coa- 

 lesce with those of the eighteenth, forming a broad and deep pervic expansion, concave 

 anteriorly, and firmly articulated with the enormously developed anterior interhaemal spine. 

 The pleurapophyses are short and slender, as in the Cod-tribe : the epipleural spinet are 

 attached to the parapophyses. These do not bifurcate and send out transverse processes, as 

 in the Plaice. The number of abdominal vertebrae in this skeleton is 1 6 ; that of the caudal 

 vertebras, 36 : total, 52. 



Purchased. 



1S3 The separated and artificially articulated bones of the head of a Halibut (Hip- 

 pcylotau vdyaru), wanting the scapular arch and its appendages. The natu- 

 ral segments of the skull and their constituent bones are denoted by numerals 

 on coloured labels, corresponding with those in No. 146, and in Table I. 



The articular surface which the basioccipital (i) presents to the atlas U almost flat. 



The supraoccipital (a) is pushed, as it were, bv the parocdpitals upon the upper surface 



