76 MATTOX 



species designated as T. occidentalis obsoleta (Dall, 1891) (Fig. 4). 

 Within the same collection variations have also been found that seem 

 to coincide with the elongated shell of Miogryphus willetti Hertlein and 

 Grant (see Plate II, figs. 5 and 6, Hertlein and Grant, 1944). On the 

 basis of these observed variations it is the writer's opinion that the species 

 T. arnoldi and M. willetti should be questioned, and that the subspecies 

 T. occidentalis obsoleta designation is untenable. Variations in shell form 

 are undoubtedly the result of diflFerences in the environmental conditions 

 in which the animals live. An examination of the gross anatomy of these 

 variants failed to indicate any significant differences. 



Terebratalia occidentalis, also of the family Terebratellidae, is an 

 older genus than Laqueus, dating back approximately 30,000,000 years 

 to the Oligocene. The geographic distribution of the living forms extends 

 from San Francisco, California, south to Cabo Lucas, Baja California. 



Another variable species of brachiopod found in the Channel Island 

 area in much smaller numbers than the above mentioned species is 

 Terebratalia transversa (Sowerby, 1846). This species has been observed 

 here only in isolated conditions, not attached to other brachiopods. The 

 variations observed range from the relatively smooth-shelled form of 

 typical T. transversa to the heavily ribbed form that has been described 

 as the subspecies T. transversa caurina (Gould, 1850) (see Figure 5). 

 The shell color ranges from grey to reddish in this area, adding to the 

 doubt as to the tenable status of the subspecies caurina designation. These 

 variations may be genetic or due to micro-ecological conditions, but in the 

 writer's opinion do not justify subspecific designation. Off the shore of 

 nearby Santa Cruz Island this species is found in larger numbers and 

 occurs there with the smaller brachiopod Terebratulina unguicula (Car- 

 penter, 1864). 



Terebratalia transversa has occurred since the Miocene, dating back 

 approximately 20,000,000 years. The geographic distribution of the liv- 

 ing form is more extensive than for T. occidentalism extending from Alaska 

 to Ensenada, Baja California. This species has been taken to a depth of 

 877 fathoms. 



The fourth species found living in the sandy bottoms of this area is 

 the inarticulate brachiopod Glottidia albida (Hinds, 1844) (Fig. 3). 

 This long-stalked, unattached species is not common here, but there are 

 indications that it may live in colonies or groups. For example, one 

 bottom-sampler collection in 45 fathoms yielded 43 individuals from a 

 2 square-foot area. Off Catalina this species has been taken at 8, 15, and 

 45 fathoms and seems to be restricted to lesser depths than the other 



