THE BURROWING BARNACLES (CIRRIPEDIA! ACROTHORACICA) 147 



the Caribbean and western Atlantic, but other species are more 

 restricted. 



Berndtia is restricted to the western Pacific, making it the most 

 restricted genus. Berndtia purpurea is Japanese, B. fossata is from 

 New Guinea, and B. nodosa is from Singapore. It is expected that 

 the latter two species will have a larger range when fully known. 

 The sole species of Balanodytes, B. taiwanus, is found on Taiwan 

 and the Marshall Islands. 



The Cryptophialidae have been discussed above regarding the 

 restricted distribution of Australophiahis melampygos. C. minutus is 

 found in southern South America, C. cordylacis is a central Pacific 

 species, while C. heterodontus and C. lanceolatus extend to Australia. 

 C. variabilis is known from West Africa, and C. wainwrighti is from 

 the Gulf of California area. 



Australophialus turbonus is known only from South Africa, as is 

 A. utinomii. 



The Trypetesidae are widespread. Trypetesa lampas is on both 

 sides of the north Atlantic, while T. habei and T. lateralis occur in 

 the western and eastern Pacific, in Japan and California, respectively. 

 T. nassarioides is in France. 



The distribution of fossil species is largely a matter of the recognition 

 and description of the forms, which is so incomplete as not to occupy 

 our time at this point. It will be sufficient to say that North America 

 and Europe have representative species. 



Several species can occupy a single shell or coral. On Heron Island, 

 Australia, a single valve of Tridacna maxima Roding yielded four 

 species of acrothoracicans representing three genera. 



The local distribution of acrothoracican species can be most in- 

 teresting. Trypetesa lateralis prefers shells of the exposed open coast, 

 and the sharp decline in numbers in shells a short distance from the 

 exposed coast is remarkable, and has led to speculation on the low 

 migration rates of hermit crabs. (Tomlinson, 1960b) 



Those species burrowing in corals often have limited areas of con- 

 centration. The distribution of Weltneria hirsuta on the reef at Coconut 

 Island, site of the Hawaii Marine Laboratory, is heavily concentrated 

 in the area immediately to the landward side of the channel traversed 

 by the Hawaii Marine Laboratory boat. 



On a given shell or coral formation there are markedly nonrandom 

 distributions. The penchant for the heavier areas of the shells without 

 periostracum already has been noted, and they prefer in general the 

 dead basal area of coral formations. Often striations in the shell will 

 orient the settling larva, as in thoracican cirripeds. 



The distribution of acrothoracicans can be remarkably nonspecific 

 regarding the host. A specimen of coral with a Spondylus attached 



