The tidal rocks raalntained large populations of cra'bs, most conspicuous among 

 ■■'Mch vras the hermit cra"b, Coenobita conpressus (Guerin)lQ* It was found in the shells of 

 various gastropods, and was especially atiundant 'between the rocks and in narrow crevices of 

 the Islote Pelado (Station 10). 



Of other cra'bs, Ocypode gaudiehaudii H. Milne Edv;ard3 and Lucas was very a'bundant 

 in Ensenada Monita, near the Isla Hedidor ( Stat Ion 26). 



Hocly 'bottom 'belov/ lo\-i water 



Rocks 'below lov;-water mark were inha'blted 'by the majority of the inverte'brates 

 found at the lo-./er level of the tidal zone. There were, hov;©ver, several groups which were 

 not found in the exposed positions a'bove low-water mark. To those 'belong the hydroids,' 

 corals, gorgoniae, sea stars, pearl and edl'ble oysters (except 0. me:cicana ) , and larger 

 hermit cra'bs. 



The algae in the shallov; water 'below low-v.'ater mark v/ere as scarce as in the tidal 

 zone. In a fei-; places I collected speci)7iens of Asparogopsis taxifonais (Delile) Collins and 

 Eervey (Station 2U, Pur.ta Pajaron) , occasional G-alaraura rugosa, and a fev; Lithotannion . 



Hydroids were frequently encountered growiiig on shells of oysters and other 

 nollusks. Unfortunate!;,-, part of njr collection containing hydroids was lost in shipment to 

 Panana and the speciaens could not Tse identified. 



The corals were rather connon, 'out never formed reefs or extensive colonies. The 

 specimens freauently brought up 'by divers 'belong to the genera Porltes and Pocillopora . 

 Occaslonall;r, round colijims of Agaric la sp. and flat and leaf-like specimens of Sldeastraea 

 sp. were o'bserved. In general, the grovrth of corals was 'by no means luxuriant, although 

 they v;ere encountered at alrost every station. With the exception of muddy 'bottoms of the 

 Bay of San Miguel, the gorgonians were a'bundant almost at every station. More freouently 

 found were the large colonies of Sorgonla steno'brochiB Valenciennes (Pig. l6) , Leptogorgla 

 laxa Hickson, gnd Leptogorgla al'ba (Duchassalng et Mlchelottl). Less freo.uent, brut still 

 rather comion, v;ere Gorgonia media (Temie) , Sorgonla pulchra (Terrill) , and Eugorgia dajnana 

 Terrill.S/ 



Hear Isleto Pelado (Station 10) , at a depth of a'bout 7 fathoms, the diver encoun- 

 tered a very large number of huge colonies of an Antlpatharlan of 'brilliant orange color. 

 The specimens 'brought up on deck measured from 5 'to 6 feet across and 6 to 7 feet in height. 

 Many live Pteria peruviana (Reeve) were attached to its branches (Pig. 17) , among which 

 crav/led small O-ohlurldae. According to the description of the diver, the bottom of the sea 

 looked like a fantastic forest of gayly decorated Christmas trees. This Antlpatharlan was 

 not found at any other station. According to a personal conmunlcation from P. M. Bayer, It 

 is apiDarently a nev/ species v/hich v;lll be described 'by him at the earliest opportunity. 



The sea stars commonly found among the rocks of the shallow littoral zone belonged 

 to the following species, kindly identified "by Austin Clark, Curator of Echinoderras in the 

 tJ. S. national Museunt Pharia pyramldata Gray, Leiaster teres 'Verrill, TTidorellia armata 

 Gray, and Phatarla unlfasclalis Graj'. Less frequent were Mltrodla bradleyi 'Verrill, 

 Pentaceraster cuningi (Gray) , and Acanthaster ellisei Gray. The latter s-oecies is represented 

 in my collection by a large specimen, whereas formerly only very small individuals of this 

 sea star were knovm. At Isla Senora y Isla SeEorita (Station 12) one specimen of Ophidlaster 

 ludv;igi was found vrhich, according to Austin Clark, is the second knovm finding of this 

 species (U. S. National' Museum, Report, IjUs, p. 25). 



Man-;- large lanelllbranchs were found attached to the rocks below lov/-water mark. 

 The most conspicuous among them were the heavy shells of Spondylus pictorum Schreiber 

 (Pig. 13) , Ostrea megodon Hanley, Pinna Lane eo lata Sov/erby, Pinctada mazatlanica Eanley, and 

 many others. 



10/ Identified by P. A. Chace, Jr., U. S» National Museum. 



11/ Identified by Dr. Frederick M. Bayer of the U. S. National Museum. 



27 



