MAMMALS OF THE TRES MARIAS ISLANDS. 19 



some huge projecting rocks lying at the water's edge, near the settle- 

 ment. Many of the females collected contained large embryos. These 

 bats were feeding on the fruit of the wild fig. 



As surmised by Dr. Merriam, 1 the record of Chceronycteris mexicana 

 from these islands, given by Mr. Thomas in the Biologia, proves to be 

 referable to the present species. In reply to a letter of inquiry, Mr. 

 Thomas states that he discovered the mistake in identification too late 

 to correct it in the Biologia, and agrees with Dr. Merriam in referring 

 his specimen to G. mutica. 



Lasiurus borealis mexicamis (Saussure). Mexican Red Bat. 



Forrer added this species to the fauna of the Tres Marias as recorded 

 by Mr. Thomas. 3 We did not see any red bats, and I doubt their being 

 found on the islands except as stragglers from the mainland. Bats 

 are such wide ranging animals it is to be expected that several addi- 

 tional species will eventually be found to occur on the islands. 



? Phocaena commimis (Lesson). Common Porpoise. 



Porpoises supposed to belong to this species were common around 

 the shores of the Tres Marias and also in bays and mouths of 

 streams or lagoons along the coast of the mainland. They were always 

 seen in the belt of shallow discolored water within a short distance of 

 the shore. As soon as blue water, with a depth of over 40 fathoms, 

 was reached, the other porpoise (Prodelphinus longirostris) was encoun- 

 tered. The common porpoise was seen in schools of 10 to 30 or 40 indi- 

 viduals swimming in loose order. At Maria Madre they came into the 

 shallow bay in front of the settlement in the early morning and followed 

 close along shore. 

 Prodelphinus longirostris (Gray). Long-nosed Porpoise. 



In the blue water between the mainland and the islands these por- 

 poises were very abundant in schools of from 100 to 200 individuals. 

 They are much slenderer and more graceful animals than the preceding 

 species. While swimming about their feeding places at sea they were 

 accompanied by swarms of terns, gaunets, and shearwaters. On one 

 occasion, while crossing to the islands, a school of about 200 porpoises 

 came directly toward us and passed under and on all sides of the boat. 

 While they were passing, the water was broken into foam on every 

 hand by their glistening black bodies, and overhead swarmed a shriek- 

 ing crowd of sea birds. Mr. Goldman made a fortunate rifle shot and 

 killed two of them, but one sank before it could be harpooned. 



'Proc. Biol. Soc. Washington, XII, pp. 13-19, footnote, January, 1898. 

 8 Biologia Ceutrali-Americaua, Mamm., p. 205, footnote. 



