410 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL.2 



and Odhner reports 22 to 23 by 15 /x for T. laticollis. In view of individ- 

 ual variation and the fact that these measurements overlap one another, it 

 does not seem possible to separate these forms on egg size, and they are all 

 considered to be T. laticollis. 



These new hosts and localities for the species extend its already wide 

 distribution. It is now reported from the following hosts and regions 

 Caranx trachurus from the Mediterranean (reported by Odhner, 1911) 

 Trachurus trachurus from the North Sea (reported by Nicoll, 1913) 

 T. trachurus from the Black Sea (reported by Wlassenko, 1931) ; Scom- 

 ber japonicus and T. trachurus from Japan (reported by Yamaguti, 

 1934, 1938) ; Auxis thazard, Gymnosarda pela?niSj and G. alletterata 

 from Tortugas, Florida; and Caranx caballus from Port Culebra, Costa 

 Rica. 



Tergestia pectinata (Linton) occurring at Beaufort, North Carolina, 

 and Tortugas, Florida, is to be considered a different species differing 

 chiefly in sucker ratio. 



Family Accacocliidae Looss, 1912 



Tetrochetus proctocolus, new species 

 (Plate45, figs. 96, 97) 



Host: Cheilichthys annulatus (Jenyns) 



Probably also (rarely) in Trachinotus rhodopus (Gill) 



and Angelichthys sp. 

 Location: Rectum 

 Locality: Galapagos Islands 



Number: One in each of 2 hosts, 3 in another of a total of 8 

 examined 



The genus Tetrochetus was named by Looss in 1912 with T. rayner- 

 ius (Nardo) as type. Dollfus (1935, p. 205-206) in a review of the 

 Accacocliidae points out that only 2 valid differences seem to separate 

 Tetrochetus from Orophocotyle Looss, 1902. These are the lack of the 

 anterior duplication of the acetabulum and the more continuous and 

 branching vitellaria in Tetrochetus. Three species of Tetrochetus are 

 known: T. raynerius (Nardo); T. coryphaenae Yamaguti, 1934; and 

 T. hamadai Fukui and Ogata, 1935. 



SPECIFIC DIAGNOSIS OF TETROCHETUS PROCTOCOLUS 



Body smooth, cylindrical, 2. to 5.4 in length by 0.442 to 1. in width; 

 forebody 0.442 to 1.012 or almost exactly the same as greatest body 



