Galeods.- 



-FISHES.- 



-NOTIDANIDAXS. 



165 



caudal being likewise undeveloped. The scales have 

 three keels, and as many points. Tlie only genns, 

 Triakis, has been detected in the seas of Japan only. 



Family VII.— MUSTELIDANS {MusteUJce). 



In the position of the fins and stigmata, and the 

 presence of nictitating membranes and spout-holes, 

 this family corresponds with the GaleiJaus and the 

 Scylliodonts. The spout-holes are large, the orbits 

 lougisb, and the nictitating membrane swells out like 

 a doubling of the under eyelid. A three-sided lappet 

 with a rounded tip embraces three-fourths of the nostril 

 above, and there is a shorter bhmt lappet on the outside 

 of the orifice. The first dorsal stands nearly midway 

 between the pectorals and ventrals, and the caudal fin 

 is short. The teeth are like tliose of a skate, being 

 flat without cusp or sharp edge, and arranged like a 

 mosaic pavement. There is but one genus, which is 

 represented in our seas by the Smooth Hound {Muskhit: 

 vulgaris). 



Family VIII.— LAMNiEDANS [Lamnada). 



These are Shaiks which have like the three imme- 

 diately preceding families, two dorsals and one anal, 

 and the first dorsal placed over the space between the 

 pectorals and ventrals, but they have spout-holes, and 

 want the nictitating membrane ; the stigmata are 

 lung, and are all before the pectorals ; the orbits are 

 roundish ; the caudal fin is crescontic, the upper lobe 

 being but slightly longer than the under one, and the 

 anal and second dorsal, wdiich are opposed to one 

 another, are both small ; the tail is keeled on each side, 

 and the spout-holes are very small. 



The dentition vaiies in the dili'ercnt genera, which are — 

 Lnmna; Ox//r/dna; Carcharodcyn; imd St'lache ; in some of whom 

 tlie teetli are tlie most fonnidable th.at occur among tlie existing 

 .Slinrkn. 



In the British seas the Lamna cornubica is not 

 uncommon. It is known, according to age, as the 

 Porbeagle or Beaumaris Shark. A white Shark of 

 formidable size is also recognized by fishermen as being 

 occasionally met with, but its proper genus has not yet 

 been ascertained. In the posthumous edition of Yar- 

 roll's "British Fishes" it is conjectured to be the C'archa- 

 rodon requietn. The Basking Shark {Selache maxima) 

 sometimes strays from its native haunts in the north 

 sea to the coasts of Scotland and Ireland. It is a 

 sluggish, and not a dangerous Shark, though one of 

 the largest of its order, and attaining a length of thirty- 

 si.\ feet and upwards. 



Family IX.— ODONTASPIDANS (Odontaspida:). 



Agreeing with the Carcharidans and the sis families 

 immediately following that group in the relative posi- 

 tion of the fins, and with the Lamna;dans in having 

 spout-holes but wanting nictitating membranes, the 

 Odcntaspidans are further characterized by their large 

 stigmata situated wholly before tlie pectorals, large 

 decond dorsal and anal, and the u]iper lobe of the 

 caudal elongated as in the Carcharidans ; they have no 



lateral caudal keel, like that of the Lamu.'edans. Tho 

 front teeth are very large, and resemble curved tlu'ee- 

 sided spike nails. The single genus Odontaspis con- 

 tains only one or two species. 



Family X.— ALOPECIANS {Ahpccia'da). 



As in the two immediately preceding families, the 

 spout-holes of this group are so small as to be often 

 overlooked ; nictitating membranes are wanting, and 

 the first dorsal is before the ventrals, but the very great 

 length of the upper lobe of the caudal furnishes a dis- 

 tinctive character. The snout is short and conical ; 

 tlie small nostril is protected above by a short maiginal 

 lappet ; there are no labial cartilages ; and the stig- 

 mata are short as in the Carcharidans, the last one 

 being over the base of the pectorals. The teeth, whicli 

 are alike in both jaws, are lancet-sha|;cd and trilateral. 

 A single species of the only genus is known in our seas 

 by the names of Fox-shark or Thresher {Alopecias 

 vulpcs), in allusion to the size of the tail, which the fish 

 employs in its combats with the Cetaceans as a thresher 

 would use a flail. 



Family XI.-CESTRACIONTS {Cciilmciclida). 



This family consists of a single genus of only tw(j 

 species, one of them Australian, where it is commonly 

 known by the name of the Nurse {Ccsiracion j)ldlUpi'^ ; 

 another inhabiting the seas of China receives the local 

 name of Kitten Shark {Cestracion zebra). This genus 

 connects existing Selachians with palajozoio fishes. TIic 

 Cestracionts have the cleft of the nostril prolonged to the 

 margin of the mouth, which is at the front of the snout, 

 and wants the superior corner-fold. The spout- lioles 

 are distinctly visible behind the eye, and the stigmata 

 are small, with the last one over the base of the pec- 

 torals. A strong spine stands in front of each dorsal, 

 and the short caudal fin has a notch on tlie under ed^je 

 of its superior lobe. The flat pavement-like teeth form 

 oblique rcjlls, like the spires of some univalves. 



Family XIL— RIIINODONTS {PJiinodonUda-). 



This family is represented by a single known species 

 (Rliinodon typicvji), which frequents the seas round tho 

 C!ape of Good Hope. It is characterized by a fiat 

 head with the mouth and nostrils at its end, a triangu- 

 lar nasal flap, very small spout-holes and stigmata, 

 diminishing in size as they recede from the head, the 

 last one being situated over the base of the pectoral. 

 The caudal is crescentic, without a notch in its upper 

 lobe; and the very small and numerous teeth are cuni- 

 cal and card-like. 



Family XIII.— NOTIDANIDANS (Notidanidw). 



This family diflers from all the preceding Selachians 

 in having only one dorsal, and from all tho order in 

 having more stigmata than five on each side. The 

 Notidanidans have an anal fin and have been called 

 •' Galeidans which want the first dorsal." The spout- 

 holes arc small and vertical, and there are no nictitating 



