Analytical Synopsis of the Order of Squali. 377 



11.— In the third year-book of the "Archiv fiir Natur- 

 geschichte" (1837), and in the second volume of the Magazine 

 of E'atiiral History (new series), a sketch of the arrangement of 

 the Plagistomes is given hy Miiller and Henle. They thus dis- 

 tributed the various forms known to them : 



§ 1, Two dorsals and one anal ; first dorsal above or behind ventrals. 

 Family Scyllia. Pristiurus Bon., Chiloscyllium MH., Hemiscyllium 

 MH., Crossorhinus MH., Ginglymostoma MH., Stegostoma MH. 

 § 2. Two dorsals and one anal ; first dorsal in front of ventrals. 

 (Family Nictitantes). 



A. Without spiracles. 



a. Teeth flat, sharp, the edges serrated or smooth. 

 1. Carcharias. 2. Scoliodon MH. 3. Zygcena. 



b. Teeth pointed, with lateral denticles, like the teeth of Scyl- 

 Hum. 



1. Tricenodon MH. Leptocharias Andr. Smith. 



B. Possessing spiracles. 



a. Teeth, flat, sharp, serrated or not serrated. 



1. Galeocerdo MH. 2. Loxodan MH. 3. Golem MH. 

 h. Teeth pointed, as in Scyllium. 



Triakis MH. 



c. Teeth pavement-like, or presenting a general continuity of sur- 

 face, as in the Skates. 



Mustelus. 

 Family Lamnoidea. 



1. Lamna. 2. Oxyrhina Agass. 3. Carcharodon Smith. 

 4. Selache. 5. Rineodon Smith. 

 Family (Odontaspides). Triglochis MH. 

 Family (Alopecia) Alopecias MH. 

 Family (Cestraciontes) Cestracion. 



§ 3. One dorsal and one anal. 

 Family (Notidani) Hexanchus Raf. Heptanchus Raf. 



§ 4. No anal. 

 Group with dorsal stings [Acanthot-hinus Blainv.). 



1. Acanthias Bonap. 2. Spinax Bonap. 3. Centrina Cuv. 

 4. Centro2ihorus MH, 



