G36 Nin. n. II. wHTTRiforsr: ox the [A[r. T), 



NEnoniis ophidiox. (Lo{>liol)i:incliii.) 



Tliis lish lias lost its t;iil tin prol);il)Iy on a«'!)mit ui the 

 ])reliensile function of the tail, but other species of lYerojthis, e. }x. 

 y. (vquoreus, do ])os.sess a \erv small one, which i-esenibles that ol" 

 S)/n<jn(ithns in niiniatinc. 



IlirrocAMPUs huevihostuis. (Lophohraucliii.) 



The Sea-horse has no caudal iin in the adult, hut the larva 

 ])ossesses a lu-ostvle and hypuials, which degenemte, pioltahly 

 owii)<,' to the prehensile hahits. 



General reinavTcs on the Catosteomi. 



Of the three families of the Catosteomi (Gasterosteida?, Cen- 

 trisci(he, and Syngnathida)) types of which have been examined, 

 the Gasterosteidie certainly are the least specialized, and the 

 Svui^nathiihe the most so, while the Centrisciihe occupy an inter- 

 mediate position, as re^ai-ds the structure of the caudal tin. This 

 order coi-respoiuls exactly with the general classification based on 

 specialized features as a whole: this bears out what is often seen 

 elsewhere, that the caudal fin may l)e useful in classifying fishes 

 among smallei' divisions, though it may not be depended upon as 

 a l)roaiI taxonoiviic featui-e. 



r E R f E S O C E S. 



JJelo.xe AC'iTS. (8conil)i'esocida'.) 



Only the smallest trace of a urostyle can be seen in the adult. 

 There are six hypural bones in all, four of which correspond to 

 the last vertebral segment ; the most anterior of these four 

 jiossesses a prominent bony process to which mu.scles are attached. 

 The neural arch to the last vertebra is very large and protects 

 the spinal cord which can be traced to the distal eiul of it. The 

 epaxial iin-suppoi-ts are liable to some variation : thei-e are some- 

 times two. and at other times three dorsal cau<lal radials ; when 

 two are pi'esent, it is on account of the third (the uuist anterior) 

 having fii.sed to the neural arch of the autejieiudtimate vertebra 

 and so constituting an epural bone : this point iii itself is evidence 

 as to the way in which epiu-als may be formeil. 



T'he variation exhil)ite(l here is ])rol)al)ly what Stanniiis 

 referred to, in 1854, when he quoted Ikluue as demonstrating the 

 fact that the (in-ray supports may be of a ilouble nature, i. e. 

 arches plus railials. /kdone, tiuMcfore, is intei'esting as being the 

 lish in which this feature, .so frequently met with elsewhere, was 

 tirst .seen. 



The penultimate vertebra never appears to possess an epural, 

 as the radial .and neural aich are always separate. 



()ii llie uiiole the ciudal fin c)f Ik'loiw attains to a fair htamlaid 



