16 CALIFORNIA ACADEMY OF SCIENCES 



21. Urolophus mundus {Gill). 

 Urolophus astcrias Jordan & Gilbert, 1882 m, p. 579. 



The tyi^es of IJ. afiterias, obtained by Gilbert at Mazatlan and Panama in 

 1881, were originally identified as U. mundus, but were afterwards distingnished 

 because of disagreement with the description of U. mundus, the types of the 

 latter being lost. The discrepancies do not now seem very important, however, 

 and it seems safe to identify U. mundus with the present species, which is abundant 

 from Panama to the Gulf of California. 



U. mundus was thought to be distinguished from other species, including 

 U. asterias, by the short caudal spine, posteriorly inserted. If, however, the original 

 description refers to the posterior point of insertion of the caudal spine, it agrees 

 with U. asterias. Measured in that way, the insertion of the spine is usually behind 

 the middle of the tail (measured from anus), and the length of the spine equals 

 distance between snout and nostrils. U. mundus is said to have the skin " beset with 

 numerous small stelliform tubercles, larger on the dorsal region," but no mention is 

 made of the row of large spinous tubercles on median line of back and tail, charac- 

 teristic of U. asterias. In U. mundus the distance of snout from hinder margin of 

 pectorals is said to equal the width of the disk, while in U. asterias the disk is 

 constantly somewhat wider (tV to tV)- If another species be discovered at Panama, 

 with disk as wide as long, with stelliform jsrickles but with no median series of 

 spines, the case will have to be reconsidered. 



Five sjiecimens were obtained by the expedition at Panama; three of them 

 are males. The females are 42 and 31 cm. long, and contain embi'yos about 

 two-thirds grown. Tiie coloration in all the specimens is uniform dark brownish 

 on upper side of disk, without the faint dusky spots found in a Mazatlan example. 

 The fringe on velum is much less conspicuous in the Panama material. None of 

 the specimens approach the closely related U. rogersi Jordan and Starks, which is 

 undoubtedly distinct. 



22. Urolophus goodei {Jordan & Bollman). 



Not obtained by the expedition. The types were dredged by the "Albatross" 

 at Station 2795, in Panama Bay, at a depth of thirty-three fathoms. Jordan and 

 Evermann (1896, p. 81) state that this species was taken in Magdalena Bay, Lower 

 California, but the present writers are unacquainted with the record. Boulenger 

 (1898-9, Vol. XIII, p. 3) lists it from the Bay of Santa Helena, near Guayaquil. 



23. Urolophus aspidurus (Jordan & Gilbert). 



Abundant at Panama, where numerous specimens were secured, all but one 

 of which are females. One contains embryos full grown. 



The following corrections and additions may be made to current descriptions: 

 The disk, taken to posterior margin of pectorals, is constantly a little broader than 

 long; its length being less than that of tail measured from posterior insertion 



