 Why was the large Kallerian not chosen for the journey?
He was followed by a roly-poly blue-skinned humanoid from Donovan's Planet, four feet high and five hundred pounds heavy. Before then, anyone could visit Earth. At the same time, we had turned away a dozen ursinoids, fifty of the reptilian natives of Ghryne, seven Sirian spiders, and no less than nineteen chlorine-breathing Procyonites wearing gas masks. I had turned away three more ursinoids, hired a vegetable from Miazan, and said no to a scaly pseudo-armadillo from one of the Delta Worlds. And now, please, there are many applicants waiting—" You'd think it would be sort of humiliating to become a specimen in a zoo, but most of these races take it as an honor.
 There were already four Kallerians in inventory.
 There were already four Kallerians in inventory.  His species was too large to travel in the group.  He was argumentative during the interview process.  His payout demands  exceeded their budget.