92 BULLET1^^ OF THE . 



On the ventral surface the pleurals are entirely absent, from the posterior 

 jugular extension. A moderate length obtains in the orbito-nasal. The curve 

 in the subrostral is very prominent, and a trifle more open than that of R. Icevis. 

 A decided curve appears in the nasal. It is difficult to determine whether the 

 median is longitudinal or transverse, it is so very short. Near the mouth, the 

 prenasals separate widely; forward, they are convergent but not connected. 

 An oral appears behind each half of the lower jaw. 



Torpedo. 



Torpedo californica (Plate XXXI.) goes much beyond the following species 

 in respect to the amount of surface covered by the tubes and tubules. On 

 the shoulders, the curve, or, better, the scapular angle of the laterals, extends 

 farther out, and, the batteries occupying a larger portion of the disk, the pleu- 

 rals are carried nearer to the margins. As in that species, pleurals and sub- 

 orbitals seem to form a continuous tube. 



The aural is longer and straighter and in front of it the cranials converge 

 more. The rostrals extend farther toward the border, and are better provided 

 with tubules than in T. mannorata. 



At the sides of the suborbitals, and the thoracic portions oF the laterals, 

 long tubules pass out upon the batteries, nearly across them. A marked con- 

 trast is presented by this distribution when compared with that of the follow- 

 ing, or of Narcine, in both of which the tubules venture little if any over the 

 surface of the batteries. A number of long tubules put out from the aural 

 toward the shoulders. Behind the angles on the pectorals formed by the 

 pleurals, there is a strong tubule with several branches; elsewhere the tubule-3 

 are simple. 



There is much irregularity in the cephalic tulies, and it is probable that 

 there is considerable variation between individuals of the species in regard 

 to suborbitals and rostrals. In fact, there is great variance in the tubes of 

 opposite sides of the head of a single specimen. This is well illustrated by 

 dissections of the head of T. occidcntalis. 



Torpedo marmorata (Plate XXXII.) accords substantially in the arrange- 

 ment of the canals with Narcine hrasiliensis, but the tubes are longer and more 

 crooked, and the tubules are of much gi-eater length. On the back over the 

 branchial region the laterals are considerably curved. Surrounding the large 

 batteries the pleurals approach very near to the front margins of the disk. 

 These tubes unite directly with the suborbitals. The occipitals are long. 

 Tlie cranials make a rather sharp curve in front of the eye, and they di.sap- 

 pear before reaching the end of the rostrum. Among the longest tubules are 

 those situated posteriorly on the pleurals and the t)rbitals, and anteriorly on 

 the laterals. 



This genus agrees with Narcine in the absence of the canals on the lower 

 surface. 



Absence of post-scapulars, or, better, the backward position of the pleurals 



